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引言

原理：利用系统的返回手势interactivePopGestureRecognizer进行实现

使用场景：返回按钮有点小，不好触发返回时，可借助右滑返回来提升用户体验

I 添加右滑返回手势

1.1 基于全局的UINavigationController基类实现

若项目有全局的UINavigationController基类，给页面添加右滑返回手势

@implementation NavigationController

- (void)viewDidLoad
{
    [super viewDidLoad];
    //设置右滑返回手势的代理为自身
    __weak typeof(self) weakself = self;
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.delegate = (id)weakself;
    }
}

#pragma mark - UIGestureRecognizerDelegate
//这个方法是在手势将要激活前调用：返回YES允许右滑手势的激活，返回NO不允许右滑手势的激活
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    if (gestureRecognizer == self.interactivePopGestureRecognizer) {
        //屏蔽调用rootViewController的滑动返回手势，避免右滑返回手势引起死机问题
        if (self.viewControllers.count < 2 ||
 self.visibleViewController == [self.viewControllers objectAtIndex:0]) {
            return NO;
        }
    }
    //这里就是非右滑手势调用的方法啦，统一允许激活
    return YES;
}

1.2 方法交换(推荐)

往UIViewController 添加forceEnableInteractivePopGestureRecognizer方法将手势返回强制加回来

@implementation UIViewController (ERPPresent13)
+ (void)load {


    
    [self addMethod:self.class method:@selector(forceEnableInteractivePopGestureRecognizer) method:@selector(kunnan_forceEnableInteractivePopGestureRecognizer)];
    
    
}

- (BOOL)kunnan_forceEnableInteractivePopGestureRecognizer {

    
    return YES;

}

II QMUI导致右滑返回没有生效的解决方法

先来看看QMUI如何实现实现右滑返回？

2.1 问题分析

QMUI使用分类UINavigationController (QMUI) 方式进行控制右滑返回，具体核心代码如下

重写viewDidLoad设置右滑返回手势的代理为自身

        ExtendImplementationOfVoidMethodWithoutArguments([UINavigationController class], @selector(viewDidLoad), ^(UINavigationController *selfObject) {
            selfObject.qmui_interactivePopGestureRecognizerDelegate = selfObject.interactivePopGestureRecognizer.delegate;
            selfObject.interactivePopGestureRecognizer.delegate = (id<UIGestureRecognizerDelegate>)selfObject;
        });

gestureRecognizerShouldBegin

这个方法是在手势将要激活前调用：返回YES允许右滑手势的激活，返回NO不允许右滑手势的激活

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
    if (gestureRecognizer == self.interactivePopGestureRecognizer) {
        BOOL canPopViewController = [self canPopViewController:self.topViewController byPopGesture:YES];
        if (canPopViewController) {
            if ([self.qmui_interactivePopGestureRecognizerDelegate respondsToSelector:_cmd]) {
                return [self.qmui_interactivePopGestureRecognizerDelegate gestureRecognizerShouldBegin:gestureRecognizer];
            } else {
                return NO;
            }
        } else {
            return NO;
        }
    }
    return YES;
}

iOS 13.4 开始会优先询问shouldReceiveEvent方法，只有返回 YES 后才会继续后续的逻辑


- (BOOL)_gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveEvent:(UIEvent *)event {
    if (gestureRecognizer == self.interactivePopGestureRecognizer) {
        NSObject <UIGestureRecognizerDelegate> *originGestureDelegate = self.qmui_interactivePopGestureRecognizerDelegate;
        if ([originGestureDelegate respondsToSelector:_cmd]) {
            BOOL originalValue = YES;
            [originGestureDelegate qmui_performSelector:_cmd withPrimitiveReturnValue:&originalValue arguments:&gestureRecognizer, &event, nil];
            if (!originalValue && [self shouldForceEnableInteractivePopGestureRecognizer]) {
                return YES;
            }
            return originalValue;
        }
    }
    return YES;
}

其中在第三步中shouldForceEnableInteractivePopGestureRecognizer调用了UINavigationControllerBackButtonHandlerProtocol协议的forceEnableInteractivePopGestureRecognizer 进行判定是否返回。在这里插入图片描述

- (BOOL)shouldForceEnableInteractivePopGestureRecognizer {
    UIViewController *viewController = [self topViewController];
    return self.viewControllers.count > 1 && self.interactivePopGestureRecognizer.enabled && [viewController respondsToSelector:@selector(forceEnableInteractivePopGestureRecognizer)] && [viewController forceEnableInteractivePopGestureRecognizer];
}

当自定义了leftBarButtonItem按钮之后，系统的手势返回就失效了。

可以通过forceEnableInteractivePopGestureRecognizer来决定要不要把那个手势返回强制加回来。当 interactivePopGestureRecognizer.enabled = NO 或者当前UINavigationController堆栈的viewControllers小于2的时候此方法无效。

自定义了leftBarButtonItem按钮

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated{
    
    viewController.hidesBottomBarWhenPushed = self.viewControllers.count == 1;

    
    if (self.viewControllers.count>0) {
        
        [self setNavigationBarHidden:NO animated:NO];
//        viewController.hidesBottomBarWhenPushed =YES;
        //设置左边按钮

        UIBarButtonItem *backItem      =nil;
        
        
        if ([viewController respondsToSelector:@selector(KNbackAction)]) {

             backItem =[[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:QCTNAVicon_left] style:0 target:viewController action:@selector(KNbackAction)];
            

            
            
        }else{
            
            backItem =[[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:QCTNAVicon_left] style:0 target:self action:@selector(backAction)];

            
            
        }
        
            viewController.navigationItem.leftBarButtonItems = @[backItem];


        



        
        
    }
    [super pushViewController:viewController animated:animated];

}

2.2 解决方法

所以当你自定义导航栏（自定义了leftBarButtonItem按钮）没采用系统的默认的实现，发生当前不可以手势返回，可先检查为什么当前状态，系统不允许你的手势返回，例如是否隐藏了 navigationBar，或者隐藏了系统的返回按钮？

比如push的时候，自定义了leftBarButtonItem按钮了，你可以采用分类方式往UIViewController 添加forceEnableInteractivePopGestureRecognizer方法将手势返回强制加回来

2.3 动态添加方法

使用场景：

在消息发送和消息转发时会用到动态添加方法

全局控制返回手势

下面的+addMethod方法有三个参数，第一个参数是要添加方法的类，第二个参数是方法的SEL，第三个参数则是提供方法实现的SEL。

使用class_getInstanceMethod()和method_getImplementation()获取相应SEL。

下方的IMP其实就是Implementation的方法缩写，获取到相应的方法实现后，然后再调用class_addMethod()方法将IMP与SEL进行绑定即可。


/**
 往类上添加新的方法与其实现
 
 @param class 相应的类
 @param methodSel 添加的方法
 @param methodSelImpl 包含方法实现的SEL
 */
+ (void)addMethod:(Class)class method:(SEL)methodSel method:(SEL)methodSelImpl {
    Method method = class_getInstanceMethod(class, methodSelImpl);
    IMP methodIMP = method_getImplementation(method);
    const char *types = method_getTypeEncoding(method);
    class_addMethod(class, methodSel, methodIMP, types);
}

往UIViewController 添加forceEnableInteractivePopGestureRecognizer方法将手势返回强制加回来

    @implementation UIViewController (ERPPresent13)
+ (void)load {

    [self addMethod:self.class method:@selector(forceEnableInteractivePopGestureRecognizer) method:@selector(kunnan_forceEnableInteractivePopGestureRecognizer)];
    
    
}

- (BOOL)kunnan_forceEnableInteractivePopGestureRecognizer {

    
    return YES;
    


}

III 相关知识点

3.1 WKWebView实现手势左滑返回上一级

        // 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];

完整初始化代码

- (WKWebView *)webView{
    if(_webView == nil){
        
        //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 设置处理接收JS方法的对象
        [wkUController addScriptMessageHandler:weakScriptMessageDelegate  name:@"jsToOcNoPrams"];
        [wkUController addScriptMessageHandler:weakScriptMessageDelegate  name:@"jsToOcWithPrams"];
        
        config.userContentController = wkUController;
        
        //以下代码适配文本大小
        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];
        
        _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];
        
        
        
        NSString *path = [[NSBundle mainBundle] pathForResource:k_localHtml4csdn ofType:nil];
        NSString *htmlString = [[NSString alloc]initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
        [_webView loadHTMLString:htmlString baseURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] bundlePath]]];
        
    }
    return _webView;
}

3.2 自定义导航条的rightBarButtonItem

自定义导航条的rightBarButtonItem，采用initWithCustomView:rightBtn设置rightBtn.frame,让文字更大，更容易点击

kunnan.blog.csdn.net/article/det…

-(void) setuprightBtn{
    
    
    UIButton *rightBtn = [UIButton buttonWithType:UIButtonTypeCustom];
    rightBtn.frame = CGRectMake(0, 0, 44, 44);
//    [rightBtn setImage:[UIImage imageNamed:@"icon_shoukuan_shaixuan_n"] forState:UIControlStateNormal];
    [rightBtn setTitle:@"编辑" forState:UIControlStateNormal];
    
    [rightBtn setTitleColor:kcellColor forState:UIControlStateNormal];

    [rightBtn addTarget:self action:@selector(gotoEditVC) forControlEvents:UIControlEventTouchUpInside];
    [rightBtn setImageEdgeInsets:UIEdgeInsetsMake(0, 22, 0, 0)];
    
    UIBarButtonItem *rightButtonItem = [[UIBarButtonItem alloc]initWithCustomView:rightBtn];
    
    
    self.navigationItem.rightBarButtonItem = rightButtonItem;

    self.navigationItem.rightBarButtonItem.customView.hidden = YES;



}

iOS小技能：右滑返回

引言