关于侧滑interactivePopGestureRecogni

类似qq的可以侧滑返回，效果不错，当你在实现的时候本来几句代码可以简洁的搞定，可是你后来就会发现一个大坑，导致的你app Crash ，crash的提示是Can't add self as subview

分析问题，根本问题的实质其实是你在执行上一个Push 或者Pop的动画期间比如0.3秒内 你又执行力Push或者Pop导致的问题出现，
经过网上查找的资料得出总结如下 上代码
1.首先你要先了解interactivePopGestureRecognizer（导航控制器的这个交互手势）其实就是方便开发者设置不同的手势和导航控制的交互设置的属性
在你的UINavigationController基类里边写下边的代码：

• UINavigationController 基类viewDidLoad方法中加入如下代码
  -(void)viewDidLoad{
  __weak MMNavController *weakSelf = self;
  if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
  self.interactivePopGestureRecognizer.delegate = weakSelf;
  self.delegate = weakSelf;
  }
  id target = self.interactivePopGestureRecognizer.delegate;
  _screenEdgePanGesture = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:target action:@selector(handleNavigationTransition:)];
  _screenEdgePanGesture.edges = UIRectEdgeLeft;
  _screenEdgePanGesture.delegate = self;
  self.delegate = self;
  [self.view addGestureRecognizer:_screenEdgePanGesture];
  }

• -(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer   *)gestureRecognizer{
      About91ViewController *childVC;
      if (self.childViewControllers.count == 3) {
          if ([[self.childViewControllers objectAtIndex:2] class] == [About91ViewController class]) {
                childVC = (About91ViewController*)[self.viewControllers objectAtIndex:2];
                if (childVC.webViewType == INVESTMENTNOW) {
                    return NO;
                }
           }
       }
      if (self.childViewControllers.count == 1) {
          return NO;
      }else if (self.childViewControllers.count ==3 &&   [[self.viewControllers  objectAtIndex:2] isKindOfClass:[JYProductDetailVC class]]){
          return NO;
      }
      return YES;
    }
  

• - (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
  {
       if ( [self respondsToSelector:@selector(interactivePopGestureRecognizer)]&&animated == YES ){
            self.interactivePopGestureRecognizer.enabled = NO;
            self.screenEdgePanGesture.enabled = NO;
        }
        [super pushViewController:viewController animated:animated];
  }
  

• - (NSArray *)popToRootViewControllerAnimated:(BOOL)animated
  {
       if ( [self respondsToSelector:@selector(interactivePopGestureRecognizer)]&& animated == YES ){
            self.interactivePopGestureRecognizer.enabled = NO;
            self.screenEdgePanGesture.enabled = NO;
       }
      return [super popToRootViewControllerAnimated:animated];
  }
  

• - (NSArray *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated {
          if( [self respondsToSelector:@selector(interactivePopGestureRecognizer)] ){
              self.interactivePopGestureRecognizer.enabled = NO;
              self.screenEdgePanGesture.enabled = NO;
          }
          return [super popToViewController:viewController animated:animated];
  }
  

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