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iOS UIWebView逐渐被淘汰, WKWebView成为主流. 本文封装了WKJSWebView(代码见第三节)，参考EasyJSWebView的交互方式, 对其进行了修改和增加. 可以实现原生调用JS, 也可以JS调用原生。

一. 使用方法

JS调原生

创建一个交互类, 定义给js的交互接口

// OC
#import <Foundation/Foundation.h>
#import "WKJSWebView.h"
@interface JSInterface : NSObject
- (void)testWithParams:(NSString*)_params callback:(WKJSDataFunction*)_callback;
@end

#import "JSInterface.h"
#import "MJExtension.h"
@implementation JSInterface
- (void)testWithParams:(NSString*)_params callback:(WKJSDataFunction*)_callback
{
    //接收h5 参数
    NSLog(@"H5 调 native, 参数 : %@", _params);
    
    NSString *letter = [NSString stringWithFormat:@"%C", (unichar)(arc4random_uniform(26) + 'A')];
    NSDictionary* p1 = @{@"letter": letter, @"b": @"bb", @"c": @"cc"};
    NSString* p2 = @"param_p2";
    NSString* p3 = @"param_p3";
    NSArray* nativeParams = @[p1, p2, p3];
    //执行h5回调函数
    [_callback executeWithParams:nativeParams completionHandler:^(id response, NSError *error) {
        NSLog(@"completionHandler");
    }];
}
@end

初始化webView

// OC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor lightGrayColor];
    
    CGRect rect = CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height-150);
    self.webView = [[WKJSWebView alloc] initWithFrame:rect configuration:[WKWebViewConfiguration new] scripts:nil withJavascriptInterfaces:@{@"native":[JSInterface new]}];
    self.webView.navigationDelegate = self;
   [self.view addSubview:self.webView];
    
    NSString* _urlStr = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];
    NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL fileURLWithPath:_urlStr]];
    [self.webView loadRequest:request];
}

JS调原生接口

<script>
  // js
  window.native.testWithParamscallback('abc', (p1, p2, p3) => {
      console.log(p1, p2, p3);
      var obj1 = JSON.parse(p1); 
      let div = document.getElementById("op");
      div.innerHTML = obj1.letter;
  });
</script>

原生调JS

js注册方法

<script>
  // js
  function changeColor(param) {
      let div = document.getElementById("oi");
      div.style.backgroundColor = param.color;
  };
  window.EasyJS.mount("divChangeColor", changeColor);
</script>

原生调用JS

// OC
NSDictionary* args = @{@"color": [self Ox_randomColor]};
[self.webView invokeJSFunction:@"divChangeColor" params:args completionHandler:^(id response, NSError *error) {
    NSLog(@"原生调用JS方法完成.");
}];

二. 原理解析

基本思想就是将需要交互的接口挂载到浏览器的window上, 然后通过js代码调用.

原生将js代码编译成字符串, 再通过下面的方法执行js:

// OC
- (void)evaluateJavaScript:(NSString *)javaScriptString completionHandler:(void (^ _Nullable)(_Nullable id, NSError * _Nullable error))completionHandler;

js调原生

注入桥接js

首先看下面的js代码:

// js
!function () {
    if (window.EasyJS) {
        return;
    }
    window.EasyJS = {
        /**
         * 存放JS的回调函数
         */
        __callbacks: {},

        /**
         * 存放JS注册给native的方法
         */
        __events: {},

        /**
         * JS执行此方法,将JS函数挂载到__events供原生调用
         * @param {String} funcName js方法名
         * @param {Function} handler js方法
         */
        mount: function (funcName, handler) {
            EasyJS.__events[funcName] = handler;
        },

        /**
         * 原生执行此方法 调用JS函数
         * @param {String} funcID js方法名
         * @param {JSON} paramsJson 参数
         */
        invokeJS: function (funcID, paramsJson) {
            let handler = EasyJS.__events[funcID];
            if (handler && typeof (handler) === 'function') {
                let args = '';
                try {
                    if (typeof JSON.parse(paramsJson) == 'object') {
                        args = JSON.parse(paramsJson);
                    } else {
                        args = paramsJson;
                    }
                    return handler(args);
                } catch (error) {
                    console.log(error);
                    args = paramsJson;
                    return handler(args);
                }
            } else {
                console.log(funcID + '函数未定义');
            }
        },

        /**
         * native通过此方法执行JS回调函数
         * @param {String} cbID 函数ID
         * @param {Boolean} removeAfterExecute 执行后是否从__callbacks中否移除此回调函数
         */
        invokeCallback: function (cbID, removeAfterExecute) {
            let args = Array.prototype.slice.call(arguments);
            args.shift(); // __cb1577786915804
            args.shift(); // false

            for (let i = 0, l = args.length; i < l; i++) {
                args[i] = decodeURIComponent(args[i]);
            }

            let cb = EasyJS.__callbacks[cbID];
            if (removeAfterExecute) {
                EasyJS.__callbacks[cbID] = undefined;
            }
            return cb.apply(null, args);
        },

        /**
         * 调用原生obj对象的方法
         * @param {String} obj 
         * @param {String} functionName 
         * @param {Array} args 
         */
        call: function (obj, functionName, args) {
            let formattedArgs = [];
            for (let i = 0, l = args.length; i < l; i++) {
                if (typeof args[i] == 'function') {
                    formattedArgs.push('f');
                    let cbID = '__cb' + (+new Date) + Math.random();
                    EasyJS.__callbacks[cbID] = args[i];
                    formattedArgs.push(cbID);
                } else {
                    formattedArgs.push('s');
                    formattedArgs.push(encodeURIComponent(args[i]));
                }
            }

            let argStr = (formattedArgs.length > 0 ? ':' + encodeURIComponent(formattedArgs.join(':')) : '');
            /** NativeListener 要与原生中addScriptMessageHandler的name保持一致 */
            window.webkit.messageHandlers.NativeListener.postMessage(obj + ':' + encodeURIComponent(functionName) + argStr);

            let ret = EasyJS.retValue;
            EasyJS.retValue = undefined;

            if (ret) {
                return decodeURIComponent(ret);
            }
        },

        /**
         * native用来给window添加obj的对象与方法
         * @param {String} obj 添加到window上的对象
         * @param {Array<String>} methods 添加到obj上的方法数组
         */
        inject: function (obj, methods) {
            window[obj] = {};
            let jsObj = window[obj];

            for (let i = 0, l = methods.length; i < l; i++) {
                (function () {
                    let method = methods[i];
                    let jsMethod = method.replace(new RegExp(':', 'g'), '');
                    jsObj[jsMethod] = function () {
                        return EasyJS.call(obj, method, Array.prototype.slice.call(arguments));
                    };
                })();
            }
        }
    };
}()

这段js在webView初始化时注入到浏览器, 在window上增加一个EasyJS对象, 为交互搭建桥梁.

// OC
//EASY_JS_INJECT_STRING是上面的js代码串
[configuration.userContentController addUserScript:[[WKUserScript alloc] initWithSource:EASY_JS_INJECT_STRING injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES]];

注入原生交互方法

然后, 继续注入原生交互类:

// OC
// interfaces : @{@"native":[JSInterface new]}
    NSMutableString* injectString = [[NSMutableString alloc] init];
    for(NSString *key in [interfaces allKeys]) {
        [injectString appendString:@"EasyJS.inject(\""];
        [injectString appendString:key];
        [injectString appendString:@"\", ["];
        NSObject* interfaceObj = [interfaces objectForKey:key];
        if ([interfaceObj isKindOfClass:[NSObject class]]) {
            Class cls = object_getClass(interfaceObj);
            while (cls != [NSObject class]) {
                unsigned int mc = 0;
                Method * mlist = class_copyMethodList(cls, &mc);
                for (int i = 0; i < mc; i++) {
                    [injectString appendString:@"\""];
                    [injectString appendString:[NSString stringWithUTF8String:sel_getName(method_getName(mlist[i]))]];
                    [injectString appendString:@"\""];
                    if ((i != mc - 1) || (cls.superclass != [NSObject class])) {
                        [injectString appendString:@", "];
                    }
                }
                free(mlist);
                cls = cls.superclass;
            }
        }
        [injectString appendString:@"]);"]; //@"EasyJS.inject(\"native\", [\"testWithParams:callback:\"]);"
    }
#ifdef DEBUG
    NSLog(@"injectString :\n%@", injectString);
#endif
    [configuration.userContentController addUserScript:[[WKUserScript alloc] initWithSource:injectString injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES]];

上面代码调用了EasyJS.inject()方法:

// js
inject: function (obj, methods) {
    window[obj] = {};
    let jsObj = window[obj];
    for (let i = 0, l = methods.length; i < l; i++) {
        (function () {
            let method = methods[i];
            let jsMethod = method.replace(new RegExp(':', 'g'), '');
            jsObj[jsMethod] = function () {
                return EasyJS.call(obj, method, Array.prototype.slice.call(arguments));
            };
        })();
    }
}

在window增加native对象,并且把JSInterface的交互方法都加到native对象.这里的native相当于JSInterface在h5中的镜像, 通过native,就可以调用原生方法:

// js
window.native.testWithParamscallback('abc', (p1, p2, p3) => {
    // h5回调函数
});

发送消息给原生

但是, native.testWithParamscallback长这样的:

// js
function() {
  return EasyJS.call(obj, method, Array.prototype.slice.call(arguments));
};

这是镜像native的testWithParamscallback方法, 它并不能换起原生, 真正调用原生的是EasyJS.call().

// js
call: function (obj, functionName, args) {
    let formattedArgs = [];
    for (let i = 0, l = args.length; i < l; i++) {
        if (typeof args[i] == 'function') {
            formattedArgs.push('f');
            let cbID = '__cb' + (+new Date) + Math.random();
            EasyJS.__callbacks[cbID] = args[i];
            formattedArgs.push(cbID);
        } else {
            formattedArgs.push('s');
            formattedArgs.push(encodeURIComponent(args[i]));
        }
    }

    let argStr = (formattedArgs.length > 0 ? ':' + encodeURIComponent(formattedArgs.join(':')) : '');
    /** NativeListener 要与原生中addScriptMessageHandler的name保持一致 */
    window.webkit.messageHandlers.NativeListener.postMessage(obj + ':' + encodeURIComponent(functionName) + argStr);

    let ret = EasyJS.retValue;
    EasyJS.retValue = undefined;

    if (ret) {
        return decodeURIComponent(ret);
    }
}

Easy.call()将js的回调函数生成唯一ID对应保存到EasyJS.__callbacks,再将唯一ID和参数按约定的方式编译放入数组 ,然后用原生约定的监听名字NativeListener发送消息给原生window.webkit.messageHandlers.NativeListener.postMessage(obj + ':' + encodeURIComponent(functionName) + argStr);

NativeListener在初始化webView时指定, 同时将原生交互类映射interfaces挂载到监听者.

// OC
// add message handler
WKJSListener *listener = [[WKJSListener alloc] init];
listener.javascriptInterfaces = interfaces;
[configuration.userContentController addScriptMessageHandler:listener name:WKJSMessageHandler];

原生接收消息并执行

js发出消息后, 原生的监听WKJSListener可以接收到:

// OC
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message {
    NSMutableArray <WKJSDataFunction *>* _funcs = [NSMutableArray new];
    NSMutableArray <NSString *>* _args = [NSMutableArray new];
    
    if ([message.name isEqualToString:WKJSMessageHandler]) {
        __weak WKJSWebView *webView = (WKJSWebView *)message.webView;
        NSString *requestString = [message body];
        // native:testWithParams%3Acallback%3A:s%3Aabc%3Af%3A__cb1577786915804
        NSArray *components = [requestString componentsSeparatedByString:@":"];
        //NSLog(@"req: %@", requestString);
        
        NSString* obj = (NSString*)[components objectAtIndex:0];
        NSString* method = [(NSString*)[components objectAtIndex:1] stringByRemovingPercentEncoding];
        NSObject* interface = [self.javascriptInterfaces objectForKey:obj];
        
        SEL selector = NSSelectorFromString(method);
        NSMethodSignature* sig = [interface methodSignatureForSelector:selector];
        if (sig.numberOfArguments == 2 && components.count > 2) {
            NSString *assertDesc = [NSString stringWithFormat:@"*** -[%@ %@]: %@",NSStringFromClass([interface class]),method,@"实际接收参数个数与js传参数不相等"];
            assertDesc = assertDesc ? : @"";
            NSAssert(NO, assertDesc);
            return;
        }
        if (!sig) {
            NSString *assertDesc = [NSString stringWithFormat:@"*** -[%@ %@]:%@",NSStringFromClass([interface class]),method,@"method signature argument cannot be nil"];
            NSAssert(NO, assertDesc);
            return;
        }
        if (![interface respondsToSelector:selector]) {
            NSAssert(NO, @"该方法未实现");
            return;
        }
        
        NSInvocation* invoker = [NSInvocation invocationWithMethodSignature:sig];
        invoker.selector = selector;
        invoker.target = interface;
        if ([components count] > 2){
            NSString *argsAsString = [(NSString*)[components objectAtIndex:2] stringByRemovingPercentEncoding];
            NSArray* formattedArgs = [argsAsString componentsSeparatedByString:@":"];
            if ((sig.numberOfArguments - 2) != [formattedArgs count] / 2) {
                NSString *assertDesc = [NSString stringWithFormat:@"*** -[%@ %@]: 实际接收参数个数%@，js传参个数%@",NSStringFromClass([interface class]),method,@(sig.numberOfArguments - 2),@([formattedArgs count] / 2)];
                assertDesc = assertDesc ? : @"";
                NSAssert(NO, assertDesc);
                return;
            }
            for (unsigned long i = 0, j = 0, l = [formattedArgs count]; i < l; i+=2, j++){
                NSString* type = ((NSString*) [formattedArgs objectAtIndex:i]);
                NSString* argStr = ((NSString*) [formattedArgs objectAtIndex:i + 1]);
                
                if ([@"f" isEqualToString:type]){
                    WKJSDataFunction *func = [[WKJSDataFunction alloc] initWithWebView:webView];
                    func.funcID = argStr;
                    [_funcs addObject:func];
                    [invoker setArgument:&func atIndex:(j + 2)];
                }else if ([@"s" isEqualToString:type]){
                    NSString* arg = [argStr stringByRemovingPercentEncoding];
                    [_args addObject:arg];
                    [invoker setArgument:&arg atIndex:(j + 2)];
                }
            }
        }
        [invoker retainArguments];
        [invoker invoke];
        
        if ([sig methodReturnLength] > 0){
            __unsafe_unretained NSString* tmpRetValue;
            [invoker getReturnValue:&tmpRetValue];
            NSString *retValue = tmpRetValue;
            
            if (retValue == NULL || retValue == nil){
                [webView wk_evaluateJavaScript:@"EasyJS.retValue=null;" completionHandler:nil];
            }else{
                retValue = [retValue stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet letterCharacterSet]];
                retValue = [@"" stringByAppendingFormat:@"EasyJS.retValue=\"%@\";", retValue];
                [webView wk_evaluateJavaScript:retValue completionHandler:nil];
            }
        }
    }
    
    [_funcs removeAllObjects];
    [_args removeAllObjects];
}

在这里取出对象,方法,参数, 通过javascriptInterfaces映射取原生对象(也就是JSInterface),然后执行方法.

执行js回调

原生方法执行后回调js:

// OC
[_callback executeWithParams:nativeParams completionHandler:^(id response, NSError *error) {
}];

executeWithParams:completionHandler:方法如下:

// OC
- (void)executeWithParams:(NSArray *)params completionHandler:(void (^)(id response, NSError *error))completionHandler {
    
    NSMutableArray * args = [NSMutableArray arrayWithArray:params];
    for (int i=0; i<params.count; i++) {
        NSString* json = [params[i] mj_JSONString];
        [args replaceObjectAtIndex:i withObject:json];
    }
    
    NSMutableString* injection = [[NSMutableString alloc] init];
    [injection appendFormat:@"EasyJS.invokeCallback(\"%@\", %@", self.funcID, self.removeAfterExecute ? @"true" : @"false"];
    
    if (args) {
        for (unsigned long i = 0, l = args.count; i < l; i++){
            NSString* arg = [args objectAtIndex:i];
            NSCharacterSet *chars = [NSCharacterSet characterSetWithCharactersInString:@"!*'();:@&=+$,/?%#[]"];
            NSString *encodedArg = [arg stringByAddingPercentEncodingWithAllowedCharacters:chars];
            [injection appendFormat:@", \"%@\"", encodedArg];
        }
    }
    
    [injection appendString:@");"];
    
    if (_webView){
        [_webView wk_evaluateJavaScript:injection completionHandler:^(id response, NSError *error) {
            if (completionHandler) {completionHandler(response, error);}
        }];
    }
}

通过EasyJS.invokeCallback()传入回调函数唯一ID, 取出__callbacks中对应的方法并执行:

// js
invokeCallback: function (cbID, removeAfterExecute) {
    let args = Array.prototype.slice.call(arguments);
    args.shift(); // __cb1577786915804
    args.shift(); // false

    for (let i = 0, l = args.length; i < l; i++) {
        args[i] = decodeURIComponent(args[i]);
    }

    let cb = EasyJS.__callbacks[cbID];
    if (removeAfterExecute) {
        EasyJS.__callbacks[cbID] = undefined;
    }
    return cb.apply(null, args);
},

args.shift()移除多余的参数.

至此, js调原生流程结束.

原生调js

js注册函数

原生调用js, 需要js将方法注册到window, 注入js中提供了mount()方法给js注册函数用:

// js
mount: function (funcName, handler) {
    EasyJS.__events[funcName] = handler;
},

mount()方法将JS函数handler存放到__events, 以便提供给原生调用.

js中注册也很简单:

// js
window.EasyJS.mount("divChangeColor", changeColor);

这样就将divChangeColor函数注册了, 它对应js中的changeColor()方法:

// js
function changeColor(param) {
    let div = document.getElementById("oi");
    div.style.backgroundColor = param.color;
};

原生调js

原生调用js函数divChangeColor:

// OC
[self.webView invokeJSFunction:@"divChangeColor" params:@{@"color": [self Ox_randomColor]} completionHandler:^(id response, NSError *error) {
    NSLog(@"原生调用JS方法完成.");
}];

invokeJSFunction:params:completionHandler:方法如下:

// OC
- (void)invokeJSFunction:(NSString*)jsFuncName params:(id)params completionHandler:(void (^)(id response, NSError *error))completionHandler {
    
    NSString *paramJson = @"";
    if (params) {  paramJson = [params mj_JSONString]; }
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\\" withString:@"\\\\"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\"" withString:@"\\\""];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\n" withString:@"\\n"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\r" withString:@"\\r"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\f" withString:@"\\f"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\u2028" withString:@"\\u2028"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\u2029" withString:@"\\u2029"];
    
    NSString *script = [NSString stringWithFormat:@"%@('%@', '%@')", @"window.EasyJS.invokeJS", jsFuncName,  paramJson];
    [self wk_evaluateJavaScript:script completionHandler:completionHandler];
}

通过EasyJS.invokeJS(),取出__events中对应divChangeColor的函数并执行.

// js
invokeJS: function (funcID, paramsJson) {
    let handler = EasyJS.__events[funcID];
    if (handler && typeof (handler) === 'function') {
        let args = '';
        try {
            if (typeof JSON.parse(paramsJson) == 'object') {
                args = JSON.parse(paramsJson);
            } else {
                args = paramsJson;
            }
            return handler(args);
        } catch (error) {
            console.log(error);
            args = paramsJson;
            return handler(args);
        }
    } else {
        console.log(funcID + '函数未定义');
    }
}

至此, 原生调用js完成.

三. WKJSWebView代码

WKJSWebView.h

#import <WebKit/WebKit.h>
#import <Foundation/Foundation.h>

#pragma mark - WKJSWebView

@interface WKJSWebView : WKWebView

- (instancetype)initWithFrame:(CGRect)frame configuration:(WKWebViewConfiguration*)configuration scripts:(NSArray<NSString*>*)scripts withJavascriptInterfaces:(NSDictionary*)interfaces;

/// 主线程执行js
- (void)wk_evaluateJavaScript:(NSString *)javaScriptString completionHandler:(void (^)(id, NSError *))completionHandler;

/// native 调用 h5 方法
- (void)invokeJSFunction:(NSString*)jsFuncName params:(id)params completionHandler:(void (^)(id response, NSError *error))completionHandler;

@end

#pragma mark - WKJSListener

@interface WKJSListener : NSObject<WKNavigationDelegate,WKScriptMessageHandler>
@property (nonatomic) NSDictionary *javascriptInterfaces;
@end


#pragma mark - WKJSDataFunction

@interface WKJSDataFunction : NSObject

@property (nonatomic, copy) NSString* funcID;
@property (nonatomic, strong) WKJSWebView *webView;
@property (nonatomic, assign) BOOL removeAfterExecute;

- (instancetype)initWithWebView:(WKJSWebView*)webView;

// 回调JS
- (void)execute:(void (^)(id response, NSError* error))completionHandler;
- (void)executeWithParam:(NSString *)param completionHandler:(void (^)(id response, NSError* error))completionHandler;
- (void)executeWithParams:(NSArray *)params completionHandler:(void (^)(id response, NSError* error))completionHandler;

@end

WKJSWebView.m

#import "WKJSWebView.h"
#import <objc/runtime.h>
#import "MJExtension.h"

static NSString * const EASY_JS_INJECT_STRING = @"!function () {\
    if (window.EasyJS) {\
        return;\
    }\
    window.EasyJS = {\
        __callbacks: {},\
        __events: {},\
        mount: function (funcName, handler) {\
            EasyJS.__events[funcName] = handler;\
        },\
        invokeJS: function (funcID, paramsJson) {\
            let handler = EasyJS.__events[funcID];\
            if (handler && typeof (handler) === 'function') {\
                let args = '';\
                try {\
                    if (typeof JSON.parse(paramsJson) == 'object') {\
                        args = JSON.parse(paramsJson);\
                    } else {\
                        args = paramsJson;\
                    }\
                    return handler(args);\
                } catch (error) {\
                    console.log(error);\
                    args = paramsJson;\
                    return handler(args);\
                }\
            } else {\
               console.log(funcID + '函数未定义');\
            }\
        },\
        invokeCallback: function (cbID, removeAfterExecute) {\
            let args = Array.prototype.slice.call(arguments);\
            args.shift();\
            args.shift();\
            for (let i = 0, l = args.length; i < l; i++) {\
                args[i] = decodeURIComponent(args[i]);\
            }\
            let cb = EasyJS.__callbacks[cbID];\
            if (removeAfterExecute) {\
                EasyJS.__callbacks[cbID] = undefined;\
            }\
            return cb.apply(null, args);\
        },\
        call: function (obj, functionName, args) {\
            let formattedArgs = [];\
            for (let i = 0, l = args.length; i < l; i++) {\
                if (typeof args[i] == 'function') {\
                    formattedArgs.push('f');\
                    let cbID = '__cb' + (+new Date) + Math.random();\
                    EasyJS.__callbacks[cbID] = args[i];\
                    formattedArgs.push(cbID);\
                } else {\
                    formattedArgs.push('s');\
                    formattedArgs.push(encodeURIComponent(args[i]));\
                }\
            }\
            let argStr = (formattedArgs.length > 0 ? ':' + encodeURIComponent(formattedArgs.join(':')) : '');\
            window.webkit.messageHandlers.NativeListener.postMessage(obj + ':' + encodeURIComponent(functionName) + argStr);\
            let ret = EasyJS.retValue;\
            EasyJS.retValue = undefined;\
            if (ret) {\
                return decodeURIComponent(ret);\
            }\
        },\
        inject: function (obj, methods) {\
            window[obj] = {};\
            let jsObj = window[obj];\
            for (let i = 0, l = methods.length; i < l; i++) {\
                (function () {\
                    let method = methods[i];\
                    let jsMethod = method.replace(new RegExp(':', 'g'), '');\
                    jsObj[jsMethod] = function () {\
                        return EasyJS.call(obj, method, Array.prototype.slice.call(arguments));\
                    };\
                })();\
            }\
        }\
    };\
}()";

static NSString * const WKJSMessageHandler = @"NativeListener";


#pragma mark - WKJSWebView

@implementation WKJSWebView

/**
 初始化WKWwebView,并将交互类的方法注入JS
 */
- (instancetype)initWithFrame:(CGRect)frame configuration:(WKWebViewConfiguration*)configuration scripts:(NSArray<NSString*>*)scripts withJavascriptInterfaces:(NSDictionary*)interfaces
{
    if (!configuration) {
        configuration = [[WKWebViewConfiguration alloc] init];
    }
    if (!configuration.userContentController) {
        configuration.userContentController = [[WKUserContentController alloc] init];
    }
    
    // add script
    for (NSString* script in scripts) {
        [configuration.userContentController addUserScript:[[WKUserScript alloc] initWithSource:script injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES]];
    }
    
    [configuration.userContentController addUserScript:[[WKUserScript alloc] initWithSource:EASY_JS_INJECT_STRING injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES]];
    
    NSMutableString* injectString = [[NSMutableString alloc] init];
    for(NSString *key in [interfaces allKeys]) {
        [injectString appendString:@"EasyJS.inject(\""];
        [injectString appendString:key];
        [injectString appendString:@"\", ["];
        NSObject* interfaceObj = [interfaces objectForKey:key];
        if ([interfaceObj isKindOfClass:[NSObject class]]) {
            Class cls = object_getClass(interfaceObj);
            while (cls != [NSObject class]) {
                unsigned int mc = 0;
                Method * mlist = class_copyMethodList(cls, &mc);
                for (int i = 0; i < mc; i++) {
                    [injectString appendString:@"\""];
                    [injectString appendString:[NSString stringWithUTF8String:sel_getName(method_getName(mlist[i]))]];
                    [injectString appendString:@"\""];
                    if ((i != mc - 1) || (cls.superclass != [NSObject class])) {
                        [injectString appendString:@", "];
                    }
                }
                free(mlist);
                cls = cls.superclass;
            }
        }
        [injectString appendString:@"]);"]; //@"EasyJS.inject(\"native\", [\"testWithParams:callback:\"]);"
    }
#ifdef DEBUG
    NSLog(@"injectString :\n%@", injectString);
#endif
    [configuration.userContentController addUserScript:[[WKUserScript alloc] initWithSource:injectString injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES]];
    
    // add message handler
    WKJSListener *listener = [[WKJSListener alloc] init];
    listener.javascriptInterfaces = interfaces;
    [configuration.userContentController addScriptMessageHandler:listener name:WKJSMessageHandler];
    
    // init
    self = [super initWithFrame:frame configuration:configuration];
    return self;
}

- (void)wk_evaluateJavaScript:(NSString *)javaScriptString completionHandler:(void (^)(id, NSError *))completionHandler {
    if (![NSThread isMainThread]) {
        dispatch_async(dispatch_get_main_queue(), ^{
            [self evaluateJavaScript:javaScriptString completionHandler:^(id _Nullable response, NSError * _Nullable error) {
                if (completionHandler) {completionHandler(response, error);}
            }];
        });
    } else {
        [self evaluateJavaScript:javaScriptString completionHandler:^(id _Nullable response, NSError * _Nullable error) {
            if (completionHandler) {completionHandler(response, error);}
        }];
    }
}

- (void)invokeJSFunction:(NSString*)jsFuncName params:(id)params completionHandler:(void (^)(id response, NSError *error))completionHandler {
    
    NSString *paramJson = @"";
    if (params) {  paramJson = [params mj_JSONString]; }
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\\" withString:@"\\\\"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\"" withString:@"\\\""];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\n" withString:@"\\n"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\r" withString:@"\\r"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\f" withString:@"\\f"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\u2028" withString:@"\\u2028"];
     paramJson = [paramJson stringByReplacingOccurrencesOfString:@"\u2029" withString:@"\\u2029"];
    
    NSString *script = [NSString stringWithFormat:@"%@('%@', '%@')", @"window.EasyJS.invokeJS", jsFuncName,  paramJson];
    [self wk_evaluateJavaScript:script completionHandler:completionHandler];
}

@end


#pragma mark - WKJSListener

@implementation WKJSListener

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message {
    NSMutableArray <WKJSDataFunction *>* _funcs = [NSMutableArray new];
    NSMutableArray <NSString *>* _args = [NSMutableArray new];
    
    if ([message.name isEqualToString:WKJSMessageHandler]) {
        __weak WKJSWebView *webView = (WKJSWebView *)message.webView;
        NSString *requestString = [message body];
        // native:testWithParams%3Acallback%3A:s%3Aabc%3Af%3A__cb1577786915804
        NSArray *components = [requestString componentsSeparatedByString:@":"];
        //NSLog(@"req: %@", requestString);
        
        NSString* obj = (NSString*)[components objectAtIndex:0];
        NSString* method = [(NSString*)[components objectAtIndex:1] stringByRemovingPercentEncoding];
        NSObject* interface = [self.javascriptInterfaces objectForKey:obj];
        
        // execute the interfacing method
        SEL selector = NSSelectorFromString(method);
        NSMethodSignature* sig = [interface methodSignatureForSelector:selector];
        if (sig.numberOfArguments == 2 && components.count > 2) {
            // 方法签名获取到实际实现的方法无参数 && js调用的方法带参数
            NSString *assertDesc = [NSString stringWithFormat:@"*** -[%@ %@]: %@",NSStringFromClass([interface class]),method,@"oc的交互方法不带参数，但是js调用的方法传了参数"];
            //  因为pod报警告，所以加上这句，实际没有意义
            assertDesc = assertDesc ? : @"";
            NSAssert(NO, assertDesc);
            return;
        }
        if (!sig) {
            NSString *assertDesc = [NSString stringWithFormat:@"*** -[%@ %@]:%@",NSStringFromClass([interface class]),method,@"method signature argument cannot be nil"];
            NSAssert(NO, assertDesc);
            return;
        }
        if (![interface respondsToSelector:selector]) {
            NSAssert(NO, @"该方法未实现");
            return;
        }
        
        NSInvocation* invoker = [NSInvocation invocationWithMethodSignature:sig];
        invoker.selector = selector;
        invoker.target = interface;
        if ([components count] > 2){
            NSString *argsAsString = [(NSString*)[components objectAtIndex:2] stringByRemovingPercentEncoding];
            NSArray* formattedArgs = [argsAsString componentsSeparatedByString:@":"];
            if ((sig.numberOfArguments - 2) != [formattedArgs count] / 2) {
                // 方法签名获取到实际实现的方法的参数个数 != js调用方法时传参个数
                NSString *assertDesc = [NSString stringWithFormat:@"*** -[%@ %@]: oc的交互方法参数个数%@，js调用方法时传参个数%@",NSStringFromClass([interface class]),method,@(sig.numberOfArguments - 2),@([formattedArgs count] / 2)];
                //  因为pod报警告，所以加上这句，实际没有意义
                assertDesc = assertDesc ? : @"";
                NSAssert(NO, assertDesc);
                return;
            }
            for (unsigned long i = 0, j = 0, l = [formattedArgs count]; i < l; i+=2, j++){
                NSString* type = ((NSString*) [formattedArgs objectAtIndex:i]);
                NSString* argStr = ((NSString*) [formattedArgs objectAtIndex:i + 1]);
                
                if ([@"f" isEqualToString:type]){
                    WKJSDataFunction *func = [[WKJSDataFunction alloc] initWithWebView:webView];
                    func.funcID = argStr;
                    //do this to force retain a reference to it
                    [_funcs addObject:func];
                    [invoker setArgument:&func atIndex:(j + 2)];
                }else if ([@"s" isEqualToString:type]){
                    NSString* arg = [argStr stringByRemovingPercentEncoding];
                    //do this to force retain a reference to it
                    [_args addObject:arg];
                    [invoker setArgument:&arg atIndex:(j + 2)];
                }
            }
        }
        [invoker retainArguments];
        [invoker invoke];
        
        //return the value by using javascript
        if ([sig methodReturnLength] > 0){
            __unsafe_unretained NSString* tmpRetValue;
            [invoker getReturnValue:&tmpRetValue];
            NSString *retValue = tmpRetValue;
            
            if (retValue == NULL || retValue == nil){
                [webView wk_evaluateJavaScript:@"EasyJS.retValue=null;" completionHandler:nil];
            }else{
                retValue = [retValue stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet letterCharacterSet]];
                retValue = [@"" stringByAppendingFormat:@"EasyJS.retValue=\"%@\";", retValue];
                [webView wk_evaluateJavaScript:retValue completionHandler:nil];
            }
        }
    }
    
    //clean up any retained funcs
    [_funcs removeAllObjects];
    //clean up any retained args
    [_args removeAllObjects];
}

@end

#pragma mark - WKJSDataFunction

@implementation WKJSDataFunction

- (instancetype)initWithWebView:(WKJSWebView *)webView {
    self = [super init];
    if (self) {
        _webView = webView;
    }
    return self;
}

- (void)execute:(void (^)(id response, NSError *error))completionHandler {
    [self executeWithParam:nil completionHandler:^(id response, NSError *error) {
        if (completionHandler) {
            completionHandler(response, error);
        }
    }];
}

- (void)executeWithParam:(NSString *)param completionHandler:(void (^)(id response, NSError *error))completionHandler {
    [self executeWithParams:param ? @[param] : nil completionHandler:^(id response, NSError *error) {
        if (completionHandler) {
            completionHandler(response, error);
        }
    }];
}

- (void)executeWithParams:(NSArray *)params completionHandler:(void (^)(id response, NSError *error))completionHandler {
    
    NSMutableArray * args = [NSMutableArray arrayWithArray:params];
    for (int i=0; i<params.count; i++) {
        NSString* json = [params[i] mj_JSONString];
        [args replaceObjectAtIndex:i withObject:json];
    }
    
    NSMutableString* injection = [[NSMutableString alloc] init];
    [injection appendFormat:@"EasyJS.invokeCallback(\"%@\", %@", self.funcID, self.removeAfterExecute ? @"true" : @"false"];
    
    if (args) {
        for (unsigned long i = 0, l = args.count; i < l; i++){
            NSString* arg = [args objectAtIndex:i];
            NSCharacterSet *chars = [NSCharacterSet characterSetWithCharactersInString:@"!*'();:@&=+$,/?%#[]"];
            NSString *encodedArg = [arg stringByAddingPercentEncodingWithAllowedCharacters:chars];
            [injection appendFormat:@", \"%@\"", encodedArg];
        }
    }
    
    [injection appendString:@");"];
    
    if (_webView){
        [_webView wk_evaluateJavaScript:injection completionHandler:^(id response, NSError *error) {
            if (completionHandler) {completionHandler(response, error);}
        }];
    }
}

@end

四. demo代码

iOS

//
//  ViewController.m
//  TMEasyJSWebView
//
//  Created by 吉久东 on 2019/8/13.
//  Copyright © 2019 JIJIUDONG. All rights reserved.
//

#import "ViewController.h"
#import "WKJSWebView.h"
#import "JSInterface.h"
#import "MJExtension.h"

@interface ViewController ()<WKNavigationDelegate>
@property (nonatomic, strong) WKJSWebView *webView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor lightGrayColor];
    
    CGRect rect = CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height-150);
    self.webView = [[WKJSWebView alloc] initWithFrame:rect configuration:[WKWebViewConfiguration new] scripts:nil withJavascriptInterfaces:@{@"native":[JSInterface new]}];
    self.webView.navigationDelegate = self;
   [self.view addSubview:self.webView];
    
    NSString* _urlStr = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];
    NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL fileURLWithPath:_urlStr]];
    [self.webView loadRequest:request];
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    
    UILabel* l = [UILabel new];
    l.text = @"这里灰色部分是原生界面";
    l.frame = CGRectMake(5, self.view.bounds.size.height - 150, 310, 20);
    [self.view addSubview:l];
    
    UIButton * b = [UIButton buttonWithType:UIButtonTypeCustom];
    b.backgroundColor = [UIColor yellowColor];
    [b setTitle:@"黄色是原生按钮" forState:UIControlStateNormal];
    [b setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [b setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
    [b addTarget:self action:@selector(nativeButtonClicked) forControlEvents:UIControlEventTouchUpInside];
    b.frame = CGRectMake(5, self.view.bounds.size.height-100, 310, 50);
    [self.view addSubview:b];
}

- (void)nativeButtonClicked {
    NSLog(@"点击了原生按钮");
    [self.webView invokeJSFunction:@"divChangeColor" params:@{@"color": [self Ox_randomColor]} completionHandler:^(id response, NSError *error) {
        NSLog(@"原生调用JS方法完成.");
    }];
}

- (NSMutableString*)Ox_randomColor {
    NSMutableString* color = [[NSMutableString alloc] initWithString:@"#"];
    NSArray * STRING = @[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"A",@"B",@"C",@"D",@"E",@"F"];
    for (int i=0; i<6; i++) {
        NSInteger index = arc4random_uniform((uint32_t)STRING.count);
        NSString *c = [STRING objectAtIndex:index];
        [color appendString:c];
    }
    return color;
}

@end

h5

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .a {
            width: 300px;
            height: 80px;
            font-size: 32px;
            text-align: center;
            line-height: 80px;
            margin-bottom: 10px;
        }
    </style>
    <script>
        function getCharacter() {
            window.native.testWithParamscallback('abc', (p1, p2, p3) => {
                console.log(p1, p2, p3);
                var obj1 = JSON.parse(p1);
                let div = document.getElementById("op");
                div.innerHTML = obj1.letter;
            });
        };

        function changeColor(param) {
            let div = document.getElementById("oi");
            div.style.backgroundColor = param.color;
        };

        window.EasyJS.mount("divChangeColor", changeColor);
    </script>
</head>

<body>
    <p>这里是 h5 web 页面</p>
    <p>1.点击下面按钮,调用原生方法获取随机字母并显示到h5</p>
    <div id="op" class="a" style="background-color: pink;" onclick="getCharacter()"></div>
    <p>2.原生调用h5方法,改变该元素背景色</p>
    <div id="oi" class="a" style="background-color: aqua;" onclick="changeColor()"></div>
</body>

</html>