问题：

当A controller作为navigationController的rootcontroller时，如果在A中向右侧滑动，再push到下个界面时会出现界面假死。原因此时导航控制器的viewControllers的count值为1，滑动时没有上层控制器，系统不知如何处理，所以会出现假死。

解决方法：

自定义导航控制器，实现如下代理

- (void)viewDidLoad {
    [super viewDidLoad];
    __weak BaseNavigationViewController *weakSelf = self;
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
    self.interactivePopGestureRecognizer.delegate = weakSelf;
    self.delegate = weakSelf;
  }
}

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

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

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

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animate {
  if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]){
        if (navigationController.childViewControllers.count == 1) {
        self.interactivePopGestureRecognizer.enabled = NO;
         }else {
          self.interactivePopGestureRecognizer.enabled = YES;
         }
   }
}