UINavigationController 全局右划导致界面假

OS原生是支持边缘滑动返回的,
但如QQ这种全屏全局右划返回显然用户体验更好,
实现起来其实也不麻烦, 但添加这个功能后可能会导致界面卡死问题,
网上的说法有很多而且不全, 其实导致这种问题会有很多种情况, 这里总结一下:

卡死的原因有三种:

1.在push或pop的过程中, 接收到新的滑动返回手势.

主要是界面切换快速操作可能出现

解决办法: 
自定义UINavigationController, 
在pushViewController/setViewControllers/popViewControllerAnimated/popToRootViewControllerAnimated中禁用手势
在代理方法- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated;中启用手势

2.在根控制器右划返回

在上面的代码中增加判断, 若子控制器数量为1, 禁用手势

3.点击navigationItem返回同时触发了手势.

一般在自定义了返回按钮出现, 例如:自定义button的手势为UIControlEventTouchDown, 全局右划返回手势作用view为self.interactivePopGestureRecognizer.view, 两者可能会同时触发

根据原因, 改变手势作用域
UIView *targetView = [[self.viewControllers lastObject] view];
或改变按钮事件触发条件
UIControlEventTouchUpInside

完整添加全局右滑返回且无BUG代码如下:

@interface LTNavigationController () <UIGestureRecognizerDelegate, UINavigationControllerDelegate>
/**
 是否允许右滑返回
 */
@property (nonatomic, assign, getter=isBackGestureEnable) BOOL backGestureEnable;

@end

@implementation LTNavigationController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.navigationBar.backgroundColor = [UIColor whiteColor];
    //设置全局右滑返回
    [self setupRightPanReturn];
    
    [self.navigationItem setHidesBackButton:YES];
    
    self.delegate = self;
}



#pragma mark ---每次push之后生成返回按钮----
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated{
    if (self.viewControllers.count > 0) {
        viewController.navigationItem.leftBarButtonItem = [UIBarButtonItem BarButtonItemWithImg:@"back_black"  highlightedImg:nil target:self action:@selector(popViewController)];
        viewController.hidesBottomBarWhenPushed = YES;
        viewController.edgesForExtendedLayout = UIRectEdgeNone;
        viewController.automaticallyAdjustsScrollViewInsets = NO;
    }
    
    // push的时候禁用手势
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.enabled = NO;
        self.backGestureEnable = NO;
    }
    
    [super pushViewController:viewController animated:animated];
}


- (void)setViewControllers:(NSArray<UIViewController *> *)viewControllers animated:(BOOL)animated{
    for (UIViewController *viewController in viewControllers) {
        if (viewController != [viewControllers firstObject]) {
            viewController.navigationItem.leftBarButtonItem = [UIBarButtonItem BarButtonItemWithImg:@"back_black"  highlightedImg:nil target:self action:@selector(popViewController)];
            viewController.hidesBottomBarWhenPushed = YES;
            viewController.edgesForExtendedLayout = UIRectEdgeNone;
            viewController.automaticallyAdjustsScrollViewInsets = NO;
        }
    }
    
    // push的时候禁用手势
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.enabled = NO;
        self.backGestureEnable = NO;
    }
    
    [super setViewControllers:viewControllers animated:animated];
}


- (void)popViewController{
    [self popViewControllerAnimated:YES];
}


- (UIViewController *)popViewControllerAnimated:(BOOL)animated{
    // pop的时候禁用手势
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.enabled = NO;
    }
    
    return [super popViewControllerAnimated:animated];
}


- (NSArray<UIViewController *> *)popToRootViewControllerAnimated:(BOOL)animated{

    // pop的时候禁用手势
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.enabled = NO;
    }
    
    return [super popToRootViewControllerAnimated:animated];
}


- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated{

    // push完成后的时候判断是否在根控制器启用手势
    if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        
        if ([navigationController.viewControllers count] == 1) {
            navigationController.interactivePopGestureRecognizer.enabled = NO;
        } else {
            self.backGestureEnable = YES;
            navigationController.interactivePopGestureRecognizer.enabled = YES;
        }
    }
}


#pragma mark ---处理全局右滑返回---
- (void)setupRightPanReturn{

    // 获取系统自带滑动手势的target对象
    id target = self.interactivePopGestureRecognizer.delegate;
    // 获取返回方法
    SEL handler = NSSelectorFromString(@"handleNavigationTransition:");
    //  获取添加系统边缘触发手势的View
        UIView *targetView = self.interactivePopGestureRecognizer.view;
    
    //  创建pan手势 作用范围是全屏
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:target action:handler];
    pan.delegate = self;
    [targetView addGestureRecognizer:pan];
    
    // 关闭边缘触发手势 防止和原有边缘手势冲突
    [self.interactivePopGestureRecognizer setEnabled:NO];
}

// 什么时候调用：每次触发手势之前都会询问下代理，是否触发。
// 作用：拦截手势触发
- (BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)gestureRecognizer{
    
    //解决与左滑手势冲突
    CGPoint translation = [gestureRecognizer translationInView:gestureRecognizer.view];
    if (translation.x <= 0 || !self.isBackGestureEnable) {
        return NO;
    }
    return self.childViewControllers.count == 1 ? NO : YES;
}

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