ios - 当应用程序进入前台时，如何重新启动基于 block 的动画？

Question

我有以下基于 block 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，完成 block 被调用，我的动画不会重新启动。我尝试使用以下委托(delegate)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];
    ......
}

但这并不能恢复动画。

同样，我已经尝试了这些问题的答案中列出的方法:

• iOS, Restarting animation when coming out of the background

• Restoring animation where it left off when app resumes from background

但是那里的所有建议都对我没有用。当应用程序从后台返回时，是否有另一种方法可以恢复基于 block 的 UIView 动画？

Answer 1

一个 friend 解决了问题，需要在 View 从后台返回时在 View 上启用动画

- (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.
     */
    [UIView enableAnimations:YES];
    [[self viewController] animate];
    ......
}

然后在 block 动画之前需要移除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");
                            }

                        }];
            }
        }
    }