删除自身作为观察者时崩溃 - CALayer

发布于 2024-08-22 19:41:50 字数 515 浏览 6 评论 0原文

当我在 -(void)dealloc 中删除自己作为观察者时，我的 CALayer 子类发生崩溃：

- (void)dealloc {
 [[NSUserDefaults standardUserDefaults] removeObserver:self forKeyPath:@"showColorLabels"];
 [colorLabel release];
 [_color release];
 [super dealloc];
}

抛出异常。它说 self 尚未被添加为观察者。这只发生在特定情况下，在调用 [CATransactionlush] 之后。

我使用 Instruments 来查看对象何时被分配。它说它是通过调用 CALayerGetPresentationLayer() 分配的。我不确定这是如何工作的，但我猜这是我原始层的副本，所以 init 从未被调用，我也从未被添加为观察者。

在删除自己之前，我如何检查我是否是观察者，或者如何判断我是否是表示层？

布里杰·麦克斯韦

原文

I am having a crash in my CALayer subclass when I remove myself as an observer in -(void)dealloc:

- (void)dealloc {
 [[NSUserDefaults standardUserDefaults] removeObserver:self forKeyPath:@"showColorLabels"];
 [colorLabel release];
 [_color release];
 [super dealloc];
}

An exception is thrown. It says that self has not been added as an observer. This only happens in a certain case, after [CATransaction flush] is called.

I used Instruments to see when the object was allocated. It says it was allocated with the call CALayerGetPresentationLayer(). I am not sure how this works, but I guess this is a copy of my original layer, so init was never called, and I was never added as an observer.

How can I either check that I am an observer before removing myself, or maybe tell if I am a presentation layer?

Bridger Maxwell

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ま柒月 2024-08-29 19:41:50

我在这里找到了一个很好的解决方案： https://stackoverflow.com/a/6714561/958017

你可以使用尝试-调用removeobserver中的catch块：

@try{
   [[NSUserDefaults standardUserDefaults] removeObserver:self forKeyPath:@"showColorLabels"];
}@catch(id anException){
   //Whatever you want to do.
}

I found a good solution here: https://stackoverflow.com/a/6714561/958017

you can use a try-catch block in your call to removeobserver:

@try{
   [[NSUserDefaults standardUserDefaults] removeObserver:self forKeyPath:@"showColorLabels"];
}@catch(id anException){
   //Whatever you want to do.
}

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