如何在viewDidDisappear中等待动画完成？

Question

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

-(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将继续执行并返回，整个视图将在动画结束前消失。 如何在动画完成之前（在“动画完成”打印的情况下）停止方法返回。

Answer 1

viewWillDisappear:animated本质上是礼貌通知。 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视图的消失。

您最好的解决方案是在UINavigationController上创建一个类别，用于创建（未经测试）等方法：

- (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];
                    }];
}

然后你可以打电话给这些而不是

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

和

- (void)popViewControllerAfterAnimationAnimated:(BOOL)animated

分别。