iOS WKWebView的使用

本文将从以下几方面介绍 WKWebView：

• WKWebView涉及的一些类

• WKWebView涉及的代理方法

• 网页内容加载进度条和title的实现

• JS和OC的交互

• 本地HTML文件的实现

一、WKWebView涉及的一些类

• WKWebView：网页的渲染与展示

#import <WebKit/WebKit.h>
 //初始化
   _webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT) configuration:config];
    // UI代理
    _webView.UIDelegate = self;
    // 导航代理
    _webView.navigationDelegate = self;
    // 是否允许手势左滑返回上一级, 类似导航控制的左滑返回
    _webView.allowsBackForwardNavigationGestures = YES;
    //可返回的页面列表, 存储已打开过的网页
   WKBackForwardList * backForwardList = [_webView backForwardList];

    //        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.chinadaily.com.cn"]];
    //        [request addValue:[self readCurrentCookieWithDomain:@"http://www.chinadaily.com.cn"] forHTTPHeaderField:@"Cookie"];
    //        [_webView loadRequest:request];
    //页面后退
    [_webView goBack];
    //页面前进
     [_webView goForward];
    //刷新当前页面
    [_webView reload];
    
    NSString *path = [[NSBundle mainBundle] pathForResource:@"JStoOC.html" ofType:nil];
    NSString *htmlString = [[NSString alloc]initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
  //加载本地html文件
    [_webView loadHTMLString:htmlString baseURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] bundlePath]]];

• WKWebViewConfiguration：为添加WKWebView配置信息

//创建网页配置对象
WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
    
// 创建设置对象
WKPreferences *preference = [[WKPreferences alloc]init];
//最小字体大小 当将javaScriptEnabled属性设置为NO时，可以看到明显的效果
preference.minimumFontSize = 0;
//设置是否支持javaScript 默认是支持的
preference.javaScriptEnabled = YES;
// 在iOS上默认为NO，表示是否允许不经过用户交互由javaScript自动打开窗口
preference.javaScriptCanOpenWindowsAutomatically = YES;
config.preferences = preference;
    
// 是使用h5的视频播放器在线播放, 还是使用原生播放器全屏播放
config.allowsInlineMediaPlayback = YES;
//设置视频是否需要用户手动播放  设置为NO则会允许自动播放
config.requiresUserActionForMediaPlayback = YES;
//设置是否允许画中画技术 在特定设备上有效
config.allowsPictureInPictureMediaPlayback = YES;
//设置请求的User-Agent信息中应用程序名称 iOS9后可用
config.applicationNameForUserAgent = @"ChinaDailyForiPad";
 //自定义的WKScriptMessageHandler 是为了解决内存不释放的问题
WeakWebViewScriptMessageDelegate *weakScriptMessageDelegate = [[WeakWebViewScriptMessageDelegate alloc] initWithDelegate:self];
//这个类主要用来做native与JavaScript的交互管理
WKUserContentController * wkUController = [[WKUserContentController alloc] init];
//注册一个name为jsToOcNoPrams的js方法
[wkUController addScriptMessageHandler:weakScriptMessageDelegate  name:@"jsToOcNoPrams"];
[wkUController addScriptMessageHandler:weakScriptMessageDelegate  name:@"jsToOcWithPrams"];
config.userContentController = wkUController;

• WKUserScript：用于进行JavaScript注入

//以下代码适配文本大小，由UIWebView换为WKWebView后，会发现字体小了很多，这应该是WKWebView与html的兼容问题，解决办法是修改原网页，要么我们手动注入JS
NSString *jSString = @"var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);";
//用于进行JavaScript注入
WKUserScript *wkUScript = [[WKUserScript alloc] initWithSource:jSString injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
[config.userContentController addUserScript:wkUScript];

• WKUserContentController：这个类主要用来做native与JavaScript的交互管理

//这个类主要用来做native与JavaScript的交互管理
WKUserContentController * wkUController = [[WKUserContentController alloc] init];
//注册一个name为jsToOcNoPrams的js方法，设置处理接收JS方法的代理
[wkUController addScriptMessageHandler:self  name:@"jsToOcNoPrams"];
[wkUController addScriptMessageHandler:self  name:@"jsToOcWithPrams"];
config.userContentController = wkUController;
//用完记得移除
//移除注册的js方法
[[_webView configuration].userContentController removeScriptMessageHandlerForName:@"jsToOcNoPrams"];
[[_webView configuration].userContentController removeScriptMessageHandlerForName:@"jsToOcWithPrams"];

• WKScriptMessageHandler：这个协议类专门用来处理监听JavaScript方法从而调用原生OC方法，和WKUserContentController搭配使用。

==注意：遵守WKScriptMessageHandler协议，代理是由WKUserContentControl设置==

//通过接收JS传出消息的name进行捕捉的回调方法
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);
    //用message.body获得JS传出的参数体
    NSDictionary * parameter = message.body;
    //JS调用OC
    if([message.name isEqualToString:@"jsToOcNoPrams"]){
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"js调用到了oc" message:@"不带参数" preferredStyle:UIAlertControllerStyleAlert];
        [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        }])];
        [self presentViewController:alertController animated:YES completion:nil];
        
    }else if([message.name isEqualToString:@"jsToOcWithPrams"]){
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"js调用到了oc" message:parameter[@"params"] preferredStyle:UIAlertControllerStyleAlert];
        [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        }])];
        [self presentViewController:alertController animated:YES completion:nil];
    }
}

二、WKWebView涉及的代理方法

• WKNavigationDelegate ：主要处理一些跳转、加载处理操作

 // 页面开始加载时调用
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
}
    // 页面加载失败时调用
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(null_unspecified WKNavigation *)navigation withError:(NSError *)error {
    [self.progressView setProgress:0.0f animated:NO];
}
    // 当内容开始返回时调用
- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation {
}
    // 页面加载完成之后调用
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    [self getCookie];
}
    //提交发生错误时调用
- (void)webView:(WKWebView *)webView didFailNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    [self.progressView setProgress:0.0f animated:NO];
}
   // 接收到服务器跳转请求即服务重定向时之后调用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation {
}
    // 根据WebView对于即将跳转的HTTP请求头信息和相关信息来决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    
    NSString * urlStr = navigationAction.request.URL.absoluteString;
    NSLog(@"发送跳转请求：%@",urlStr);
    //自己定义的协议头
    NSString *htmlHeadString = @"github://";
    if([urlStr hasPrefix:htmlHeadString]){
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"通过截取URL调用OC" message:@"你想前往我的Github主页?" preferredStyle:UIAlertControllerStyleAlert];
        [alertController addAction:([UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        }])];
        [alertController addAction:([UIAlertAction actionWithTitle:@"打开" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
            NSURL * url = [NSURL URLWithString:[urlStr stringByReplacingOccurrencesOfString:@"github://callName_?" withString:@""]];
            [[UIApplication sharedApplication] openURL:url];
        }])];
        [self presentViewController:alertController animated:YES completion:nil];
        decisionHandler(WKNavigationActionPolicyCancel);
    }else{
        decisionHandler(WKNavigationActionPolicyAllow);
    }
}
    
    // 根据客户端受到的服务器响应头以及response相关信息来决定是否可以跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{
    NSString * urlStr = navigationResponse.response.URL.absoluteString;
    NSLog(@"当前跳转地址：%@",urlStr);
    //允许跳转
    decisionHandler(WKNavigationResponsePolicyAllow);
    //不允许跳转
    //decisionHandler(WKNavigationResponsePolicyCancel);
}
    //需要响应身份验证时调用 同样在block中需要传入用户身份凭证
- (void)webView:(WKWebView *)webView didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable credential))completionHandler{
    //用户身份信息
    NSURLCredential * newCred = [[NSURLCredential alloc] initWithUser:@"user123" password:@"123" persistence:NSURLCredentialPersistenceNone];
    //为 challenge 的发送方提供 credential
    [challenge.sender useCredential:newCred forAuthenticationChallenge:challenge];
    completionHandler(NSURLSessionAuthChallengeUseCredential,newCred);
}
    //进程被终止时调用
- (void)webViewWebContentProcessDidTerminate:(WKWebView *)webView{
}

• WKUIDelegate ：主要处理JS脚本，确认框，警告框等

 /**
     *  web界面中有弹出警告框时调用
     *
     *  @param webView           实现该代理的webview
     *  @param message           警告框中的内容
     *  @param completionHandler 警告框消失调用
     */
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler {
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"HTML的弹出框" message:message?:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler();
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
}
    // 确认框
    //JavaScript调用confirm方法后回调的方法 confirm是js中的确定框，需要在block中把用户选择的情况传递进去
- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler{
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"" message:message?:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:([UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(NO);
    }])];
    [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(YES);
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
}
    // 输入框
    //JavaScript调用prompt方法后回调的方法 prompt是js中的输入框 需要在block中把用户输入的信息传入
- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * _Nullable))completionHandler{
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:prompt message:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
        textField.text = defaultText;
    }];
    [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(alertController.textFields[0].text?:@"");
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
}
    // 页面是弹出窗口 _blank 处理
- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures {
    if (!navigationAction.targetFrame.isMainFrame) {
        [webView loadRequest:navigationAction.request];
    }
    return nil;
}

三、网页内容加载进度条和title的实现

//添加监测网页加载进度的观察者
[self.webView addObserver:self               forKeyPath:@"estimatedProgress"                  options:0                  context:nil];
//添加监测网页标题title的观察者
[self.webView addObserver:self               forKeyPath:@"title"                  options:NSKeyValueObservingOptionNew                  context:nil];

//kvo 监听进度 必须实现此方法
-(void)observeValueForKeyPath:(NSString *)keyPath
                 ofObject:(id)object
                   change:(NSDictionary<NSKeyValueChangeKey,id> *)change
                  context:(void *)context{
if ([keyPath isEqualToString:NSStringFromSelector(@selector(estimatedProgress))]
    && object == _webView) {
   NSLog(@"网页加载进度 = %f",_webView.estimatedProgress);
    self.progressView.progress = _webView.estimatedProgress;
    if (_webView.estimatedProgress >= 1.0f) {
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            self.progressView.progress = 0;
        });
    }
}else if([keyPath isEqualToString:@"title"]
         && object == _webView){
    self.navigationItem.title = _webView.title;
}else{
    [super observeValueForKeyPath:keyPath                         ofObject:object                           change:change                          context:context];
}
}
//移除观察者
[_webView removeObserver:self
              forKeyPath:NSStringFromSelector(@selector(estimatedProgress))];
[_webView removeObserver:self
              forKeyPath:NSStringFromSelector(@selector(title))];

四、JS和OC的交互

• JS调用OC

==这个实现主要是依靠WKScriptMessageHandler协议类和WKUserContentController两个类：WKUserContentController对象负责注册JS方法，设置处理接收JS方法的代理，代理遵守WKScriptMessageHandler，实现捕捉到JS消息的回调方法，详情可以看第一步中对这两个类的介绍。==

//这个类主要用来做native与JavaScript的交互管理
WKUserContentController * wkUController = [[WKUserContentController alloc] init];
//注册一个name为jsToOcNoPrams的js方法，设置处理接收JS方法的代理
[wkUController addScriptMessageHandler:self  name:@"jsToOcNoPrams"];

[wkUController addScriptMessageHandler:self  name:@"jsToOcWithPrams"];
config.userContentController = wkUController;

==注意：遵守WKScriptMessageHandler协议，代理是由WKUserContentControl设置==

 //通过接收JS传出消息的name进行捕捉的回调方法  js调OC
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);
}

• OC调用JS

//OC调用JS  changeColor()是JS方法名，completionHandler是异步回调block
NSString *jsString = [NSString stringWithFormat:@"changeColor('%@')", @"Js参数"];
[_webView evaluateJavaScript:jsString completionHandler:^(id _Nullable data, NSError * _Nullable error) {
    NSLog(@"改变HTML的背景色");
}];
    
//改变字体大小 调用原生JS方法
NSString *jsFont = [NSString stringWithFormat:@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '%d%%'", arc4random()%99 + 100];
[_webView evaluateJavaScript:jsFont completionHandler:nil];