iphone - 如何等待动画在 viewDidDisappear 中完成？

Question

我想在让 UIViewController 消失之前使用动画隐藏导航栏。因此我实现了以下内容:

-(void) viewWillDisappear:(BOOL) animated {
    [UIView transitionWithView:self.view
                      duration:UINavigationControllerHideShowBarDuration
                       options:UIViewAnimationCurveEaseOut
                    animations:^{ 
        [self.navigationController setNavigationBarHidden:YES];     
    }
                    completion:^(BOOL finished){
                    NSLog(@"animation finished");
    }];

     [super viewWillDisappear:animated];
}

问题是 viewWillDisappear 会继续执行并返回，整个 View 会在动画结束前消失。我怎样才能阻止方法在动画完成之前返回(打印“动画完成”的地方)。

Answer 1

viewWillDisappear:animated 本质上是一个礼貌的通知。它只是在它发生之前告诉你即将发生的事情。您实际上无法阻止或延迟 View 的消失。

您最好的解决方案是在 UINavigationController 上创建一个类别，该类别创建诸如(未测试)的方法:

- (void)pushViewControllerAfterAnimation:(UIViewController *)viewController animated:(BOOL)animated {
    [UIView transitionWithView:viewController.view
                      duration:UINavigationControllerHideShowBarDuration
                       options:UIViewAnimationCurveEaseOut
                    animations:^{ 
                        [self.navigationController setNavigationBarHidden:NO];     
                    }
                    completion:^(BOOL finished){
                        NSLog(@"animation finished");
                        [self pushViewController:viewController animated:animated];
                    }];
}

- (void)popViewControllerAfterAnimationAnimated:(BOOL)animated {
    [UIView transitionWithView:self.visibleViewController.view
                      duration:UINavigationControllerHideShowBarDuration
                       options:UIViewAnimationCurveEaseOut
                    animations:^{ 
                        [self.navigationController setNavigationBarHidden:YES];     
                    }
                    completion:^(BOOL finished){
                        NSLog(@"animation finished");
                        [self popViewControllerAnimated:animated];
                    }];
}

然后你可以调用这些而不是

- (void)pushViewControllerAfterAnimation:(UIViewController *)viewController animated:(BOOL)animated

和

- (void)popViewControllerAfterAnimationAnimated:(BOOL)animated

分别。