【OC】UINavController常见问题【转】

一、手势右滑返回效果失效

在我们经常使用的APP中，已经习惯右滑返回这个效果，可是我发现我们的APP中这个功能失效了，只能点击左上角的返回按钮才能执行返回这个效果。后来查了一下发现，导致这个问题的原因是因为我们自己自定义了左上角的leftBarButtonItem，我们自定义了这个BarButtonItem使得系统不能捕获pop手势了。

解决方法：

创建一个UINavigationController的子类LGJBaseNavController，该类@interface LGJBaseNavController ()，所有的关于导航控制器的操作都在这个类里面操作。

1 设置手势的delegate为self，导航控制器的delegate也为self。

- (void)viewDidLoad {
    [super viewDidLoad];
    __weak LGJBaseNavController *weakSelf = self;

    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
  
    self.interactivePopGestureRecognizer.delegate = weakSelf;
    self.delegate = weakSelf;
    }
}
 
- (UIViewController *)popViewControllerAnimated:(BOOL)animated {
  
    return [super popViewControllerAnimated:animated];
}

2 在转场/过渡的时候禁用 interactivePopGestureRecognizer当用户在转场的时候触发一个后退手势，这时候容易各种其他事件也会被唤醒，导航栈或边混乱。那么在转场效果的过程中禁用手势识别,当新的视图控制器加载完成后再启用。

#pragma mark - UINavigationControllerDelegate

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {

    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
       
       self.interactivePopGestureRecognizer.enabled = NO;
    }
    //设置返回按钮
    if (self.viewControllers.count > 0) {
 
        viewController.navigationItem.leftBarButtonItem = [self backButtonItem];
    }
    [super pushViewController:viewController animated:animated];
}

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
         
        self.interactivePopGestureRecognizer.enabled = YES;
    }
}

3 使navigationcontroller中第一个控制器不响应右滑pop手势

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
 
    if ([self.childViewControllers count] == 1) {
         
        return NO;
    }
    return YES;
}

4 解决多个手势冲突 同时接受多个手势

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

    return YES;
}

5 解决在手指滑动时候,被pop的viewController中的UIscrollView会跟着一起滚动

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    
    return [gestureRecognizer isKindOfClass:UIScreenEdgePanGestureRecognizer.class];
}

关于这个处理复杂手势冲突的方法有几个类似的手势代理方法：

//手指触摸屏幕后回调的方法，返回NO则不再进行手势识别，方法触发等

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;

//开始进行手势识别时调用的方法，返回NO则结束，不再触发手势

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer;

//是否支持多时候触发，返回YES，则可以多个手势一起触发方法，返回NO则为互斥

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

//下面这个两个方法也是用来控制手势的互斥执行的

//这个方法返回YES，第一个手势和第二个互斥时，第一个会失效

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

//这个方法返回YES，第一个和第二个互斥时，第二个会失效

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

可以将这几个方法写在一个UINavigationController的子类里面，然后在AppDelegate中设置self.window.rootViewController = [[LGJBaseNavController alloc] initWithRootViewController:vc1];可以处理全局的导航控制器关于这个右滑手势返回失效的问题，我以上写的这些方法直接写在里面就可以。另外说一句，在这个LGJBaseNavController中可以设置导航栏的一些自定义样式：比如这种样式就可以在LGJBaseNavController初始化中设置：

1496369431733830.png

navBar.png

+ (void)initialize {

    //bar样式
    UINavigationBar *bar = [UINavigationBar appearance];
    [bar setBarStyle:UIBarStyleDefault];
    [bar setBarTintColor:[UIColor blackColor]];
    [bar setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor whiteColor],NSForegroundColorAttributeName, nil]];

    //barButton样式    
    UIBarButtonItem *item = [UIBarButtonItem appearance];
     
    //Normal   
    NSMutableDictionary *textAtts = [NSMutableDictionary dictionary];
    textAtts[NSForegroundColorAttributeName] = [UIColor orangeColor];
    textAtts[NSFontAttributeName] = [UIFont systemFontOfSize:13];

    [item setTitleTextAttributes:textAtts forState:UIControlStateNormal];
        
    //不可用状态    
    NSMutableDictionary *disableTextAtts = [NSMutableDictionary dictionary];

    disableTextAtts[NSForegroundColorAttributeName] = [UIColor colorWithRed:123/255.0 green:123/255.0 blue:123/255.0 alpha:1];
        
    disableTextAtts[NSFontAttributeName] = [UIFont systemFontOfSize:13];
    [item setTitleTextAttributes:disableTextAtts forState:UIControlStateDisabled];
}

二、隐藏NavigationBar返回时，上面会有空缺

这个应该也是我们经常见的效果，比如vc1跳转vc2，vc2的导航栏是隐藏的，当从vc2返回vc1时，在这个过程中，放慢看上面会有缺失一块，放快了看就是闪屏，这个效果对用户也是不友好的，这个解决方法比较简单。就是在次级viewControleller中在设置setNavigationBarHidden时这样设置： <重要的是后面的animated参数>

- (void)viewWillAppear:(BOOL)animated {

    [super viewWillAppear:animated];
    [self.navigationController setNavigationBarHidden:YES animated:animated];
}

- (void)viewWillDisappear:(BOOL)animated {
    
    [super viewWillDisappear:animated];
    [self.navigationController setNavigationBarHidden:NO animated:animated];
}

注：此文章为转载，原文地址：http://www.cocoachina.com/ios/20170602/19418.html