如何在viewDidDisappear中等待動畫完成？

Question

我想在讓UIViewController消失之前使用動畫隱藏導航欄。 因此我實施了以下內容：

-(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];
}

問題是viewWillDisappear將繼續執行並返回，整個視圖將在動畫結束前消失。 如何在動畫完成之前（在“動畫完成”打印的情況下）停止方法返回。

Answer 1

viewWillDisappear:animated本質上是禮貌通知。 它只是在它發生之前告訴你即將發生的事情。 您實際上無法阻止或延遲視圖的消失。

您最好的解決方案是在UINavigationController上創建一個類別，用於創建（未經測試）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];
                    }];
}

然后你可以打電話給這些而不是

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

和

- (void)popViewControllerAfterAnimationAnimated:(BOOL)animated

分別。