右滑返回interactivePopGestureRecognizer<转>

最新推荐文章于 2020-12-21 11:41:21 发布

转载最新推荐文章于 2020-12-21 11:41:21 发布 · 181 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/deng37s/p/7086384.html

本文详细解析了iOS中右滑返回功能的实现原理与常见问题解决方法，包括自定义导航栏、手势冲突处理及UIScrollView上的手势失灵问题。

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右滑手势返回

//自定义baseVC中
- (void)viewDidLoad {
    [super viewDidLoad];
//    self.view.backgroundColor = ViewBgColor;
    [self.navigationController.navigationBar setBarStyle:UIBarStyleBlack];
    self.automaticallyAdjustsScrollViewInsets=NO;
    if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)])
    {
        self.navigationController.interactivePopGestureRecognizer.enabled = YES;
        if ([[UIApplication sharedApplication].activityViewController isKindOfClass:NSClassFromString(@"YMWelComeViewController")]) {
            self.navigationController.interactivePopGestureRecognizer.enabled = NO;
        }
        self.navigationController.interactivePopGestureRecognizer.delegate = self;
    }
    [self initNavBar];
}

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer*)gestureRecognizer {
　　//设置跟vc不可右滑
    if ([[UIApplication sharedApplication].activityViewController isKindOfClass:NSClassFromString(@"YMHomePageViewController")] ||
        [[UIApplication sharedApplication].activityViewController isKindOfClass:NSClassFromString(@"YMMineViewController")] ||
        [[UIApplication sharedApplication].activityViewController isKindOfClass:NSClassFromString(@"YMOrderViewController")] ||
        [[UIApplication sharedApplication].activityViewController isKindOfClass:NSClassFromString(@"YMVipCardViewController")] ||
        [[UIApplication sharedApplication].activityViewController isKindOfClass:NSClassFromString(@"YMWelComeViewController")]
        ) {
        return NO;
    }
   //冲突后--无效
    if(self.navigationController.childViewControllers.count == 1){
        // 表示用户在根控制器界面，就不需要触发滑动手势，
        return NO;
    }
    return YES;
}

ios7开始苹果增加了页面右滑返回的效果；具体的是以UINavigationController为容器的ViewController间右滑切换页面。
代码里的设置是：

 self.navigationController.interactivePopGestureRecognizer.enabled = YES;（default is YES）

可以看到苹果给navigationController添加了一个手势（具体为UIScreenEdgePanGestureRecognizer（边缘手势，同样是ios7以后才有的）），就是利用这个手势实现的 ios7的侧滑返回。

问题1：然而事情并非我们想的那么简单。
1.当我们用系统的UINavigationController，并且也是利用系统的navigateBar的时候，是完全没有问题的
2.但是当我们没有用系统的navigateBar或者自定义了返回按钮的时候，这个时候右滑返回是失效的。

解决（问题1）办法：对于这种失效的情况，考虑到interactivePopGestureRecognizer也有delegate属性，替换默认的self.navigationController.interactivePopGestureRecognizer.delegate来配置右滑返回的表现也是可行的。
我们可以在主NavigationController中设置一下：

  self.navigationController.interactivePopGestureRecognizer.delegate =(id)self

问题2：
但是出现很多问题，比如说在rootViewController的时候这个手势也可以响应，导致整个程序页面不响应；push了多层后，快速的触发两次手势，也会错乱

解决（问题2）办法：

  @interface NavRootViewController : UINavigationController
    @property(nonatomic,weak) UIViewController* currentShowVC; @end @implementation NavRootViewController -(id)initWithRootViewController:(UIViewController *)rootViewController { NavRootViewController* nvc = [super initWithRootViewController:rootViewController]; self.interactivePopGestureRecognizer.delegate = self; nvc.delegate = self; return nvc; } -(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated{ } -(void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated{ if (navigationController.viewControllers.count == 1) self.currentShowVC = Nil; else self.currentShowVC = viewController; } -(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{ if (gestureRecognizer == self.interactivePopGestureRecognizer) { return (self.currentShowVC == self.topViewController); //the most important } return YES; } @end

问题三：
UIScrollView上手势失灵：经研究，发现是UIScrollView上已经添加了 panGestureRecognizer（滑动）手势

【解决方案】
1.
苹果以UIGestureRecognizerDelegate的形式，支持多个UIGestureRecognizer共存。其中的一个方法是：

 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer;

一句话总结就是此方法返回YES时，手势事件会一直往下传递，不论当前层次是否对该事件进行响应。

  @implementation UIScrollView (AllowPanGestureEventPass)
  - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{ if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]] && [otherGestureRecognizer isKindOfClass:[UIScreenEdgePanGestureRecognizer class]]){ return YES; }else { return NO; } }

这种方式就是建一个UISCrollVIew的category，然后我用的时候是全局用的，不知道为什么在快速返回上一层的时候并快速点击会照成线程卡死。还有就是两个手势共存，所以在返回上一层的过程中，UIScrollerView还会滚动

2.
事实上，对UIGestureRecognizer来说，它们对事件的接收顺序和对事件的响应是可以分开设置的，即存在接收链和响应链。接收链如上文所述，和UIView绑定，由UIView的层次决定接收顺序。
而响应链在apple君的定义下，逻辑出奇的简单，只有一个方法可以设置多个gestureRecognizer的响应关系：

 - (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;


  //从UINavigationController里得到这个边缘手势
  @implementation UINavigationController (iOS7Support) @dynamic screenEdgePanGestureRecognizer; - (UIScreenEdgePanGestureRecognizer *)screenEdgePanGestureRecognizer{ UIScreenEdgePanGestureRecognizer *screenEdgePanGestureRecognizer = nil; if (self.view.gestureRecognizers.count > 0){ for (UIGestureRecognizer *recognizer in self.view.gestureRecognizers){ if ([recognizer isKindOfClass:[UIScreenEdgePanGestureRecognizer class]]){ screenEdgePanGestureRecognizer = (UIScreenEdgePanGestureRecognizer *)recognizer; break; } } } return screenEdgePanGestureRecognizer; } @end //当screenEdgePanGestureRecognizer生效时，UIScrollerView的panGestureRecognizer失效，这样就解决了冲突 UIScreenEdgePanGestureRecognizer *screenEdgePanGestureRecognizer = self.navigationController.screenEdgePanGestureRecognizer; [_scrollerView.panGestureRecognizer requireGestureRecognizerToFail:screenEdgePanGestureRecognizer];

全屏的右滑返回

FDFullscreenPopGesture这个开源项目里用运行时很简单的实现了全屏的右滑返回。

有人说直接用下面这种kvo的方式就能实现了，这是系统原有的私有属性，增大那个响应区域就可以了。但我自己还没实测过，有兴趣的可以试试。

[self.interactivePopGestureRecognizer setValue:@([UIScreen mainScreen].bounds.size.width) forKeyPath:@"_recognizer._settings._edgeSettings._edgeRegionSize"];