iphone - UI 卡住并以动画方式删除 UIScrollView subview

Question

在我的 iPhone 应用程序中，我有一个带有自定义内容 View 的 UIScrollView。在某些时候，自定义弹出 View 会动态添加到内容中，并带有出现和消失的缩放动画。我使用基于 block 的动画和一个完成处理程序，该处理程序调用 [self removeFromSuperView]，如下所示:

- (void)dismissPopup {
    CGRect rect = self.frame;
    rect.origin.y += rect.size.height/2 * (pointingDown ? 1 : -1);
    [UIView animateWithDuration:kZoomDuration
                     animations:^{
                         self.frame = rect;
                         self.transform = CGAffineTransformMakeScale(0.01, 0.01);
                     }
                     completion:^(BOOL finished) {
                         [self removeFromSuperview];
                     }];
}

大多数情况下这是有效的，但是在这个动画之后，UI 会时不时地完全锁定并且对任何触摸都没有响应。我很确定这个动画是问题的根源，因为动画代码被注释掉了，我无法重现它。使用调试器进行中断，所有三个线程似乎都处于空闲状态:

Thread-1
#0  0x32fd1c98 in mach_msg_trap
#1  0x32fd3d6a in mach_msg
#2  0x34432c3e in __CFRunLoopServiceMachPort
#3  0x344324c8 in __CFRunLoopRun
#4  0x34432276 in CFRunLoopRunSpecific
#5  0x3443217e in CFRunLoopRunInMode
#6  0x3026b5f2 in GSEventRunModal
#7  0x3026b69e in GSEventRun
#8  0x31ad0122 in -[UIApplication _run]
#9  0x31ace12e in UIApplicationMain
#10 0x00002b06 in main at main.m:14

Thread-2
#0  0x32ffe330 in kevent
#1  0x330a7b74 in _dispatch_mgr_invoke
#2  0x330a75c4 in _dispatch_queue_invoke
#3  0x330a7764 in _dispatch_worker_thread2
#4  0x3304b680 in _pthread_wqthread

Thread-3
#0  0x32fd1c98 in mach_msg_trap
#1  0x32fd3d6a in mach_msg
#2  0x34432c3e in __CFRunLoopServiceMachPort
#3  0x344324c8 in __CFRunLoopRun
#4  0x34432276 in CFRunLoopRunSpecific
#5  0x3443217e in CFRunLoopRunInMode
#6  0x34b524e8 in RunWebThread
#7  0x3304b284 in _pthread_start

Instruments 显示我的应用程序不占用 CPU 时间，因此存在某种死锁。谁能阐明这种行为以及如何避免这种行为？

更新:我做了更多挖掘并使用传统动画 API，该错误似乎也消失了。这可能是新动画框架中的一个错误吗？

- (void)dismissPopup {
    CGRect rect = self.frame;
    rect.origin.y += rect.size.height/2 * (pointingDown ? 1 : -1);
    [UIView beginAnimations:@"dismissPopup" context:nil];
    [UIView setAnimationDuration:kZoomDuration];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];
    self.frame = rect;
    self.transform = CGAffineTransformMakeScale(0.01, 0.01);
    [UIView commitAnimations];
}

- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
    [self removeFromSuperview];
}

Answer 1

您应该为您的动画尝试这种方法:+animateWithDuration:delay:options:animations:completion:

带有选项:UIViewAnimationOptionAllowUserInteraction