Question

我有以下基于块的动画：

[UIView animateWithDuration:0.5f delay:0.0f 
                    options:UIViewAnimationOptionRepeat|UIViewAnimationOptionAutoreverse|UIViewAnimationOptionAllowUserInteraction|UIViewAnimationOptionCurveEaseInOut
                    animations:^{
                [view.layer setTransform:CATransform3DMakeScale(1.3f, 1.3f, 1.0f)];
                NSLog(@"animating");
                    }completion:^(BOOL finished){
                        NSLog(@"Completed");
                    }];

当应用程序从后台返回时，将调用完成块，并且我的动画不会重新启动。我尝试使用以下委托方法重新启动动画：

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    /*
     Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
     */
    [[self viewController] animate];
    ......
}

但这并没有恢复动画效果。

同样，我尝试了这些问题的答案中列出的方法：

但那里没有任何建议对我有用。当应用程序从后台返回时，还有另一种方法可以恢复基于块的UIView动画吗？

Answer 1

一位朋友发现了问题，需要在视图从背景返回时启用视图

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    /*
     Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
     */
    [UIView enableAnimations:YES];
    [[self viewController] animate];
    ......
}

然后在块动画之前需要删除AllAnimations并将layer.transform设置为Identity

hasStarted = YES;
    for(UIButton * button in goldenBreakOutButtons){
        for (UIView* view in button.subviews) {
            if (wasStarted) {
                [view.layer removeAllAnimations];
                view.layer.transform = CATransform3DIdentity;
            }
            if ([view isKindOfClass:[UIImageView class]]) {
                [UIView animateWithDuration:0.5f delay:0.0f 
                        options:UIViewAnimationOptionAutoreverse|UIViewAnimationOptionAllowUserInteraction|UIViewAnimationOptionCurveEaseInOut|UIViewAnimationOptionRepeat
                        animations:^ {
                            [view.layer setTransform:CATransform3DMakeScale(1.3f, 1.3f, 1.0f)];
                            NSLog(@"animating");
                        }
                        completion:^(BOOL finished){
                            if (finished) {
                                NSLog(@"Completed");
                            }

                        }];
            }
        }
    }

Answer 2

请尝试在ViewController中订阅/取消订阅标准（ UIApplicationWillEnterForegroundNotification ）通知
来自 NSNotificationCenter ：

 

    -(void) loadView
    {
    .....
    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(restartAnimation)    
                                                 name:UIApplicationWillEnterForegroundNotification 
                                               object:nil];      
    ....
    }

    - (void) viewDidUnload
    {
    ...
      [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                      name:UIApplicationWillEnterForegroundNotification 
                                                    object:nil];
    ....
    }

    -(void) dealloc
    {
      [[NSNotificationCenter defaultCenter] removeObserver:self];
      [super dealloc];
    }

    - (void) restartAnimation
    {
        if(self.logoImageView)
        {
            [logoImageView.layer removeAllAnimations];

            CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"];

            animation.fromValue       = [NSNumber numberWithFloat:1.0];
            animation.toValue         = [NSNumber numberWithFloat:0.6];
            animation.duration        = 1.5f;
            animation.timingFunction  = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
            animation.autoreverses    = YES;
            animation.repeatCount     = HUGE_VALF;

            [[logoImageView layer] addAnimation:animation forKey:@"hidden"];
        }
    }

当应用程序到达前台时，如何重新启动基于块的动画？

2 个答案: