[英]View is not animated when it's removed from superView
我尝试在屏幕外动画后从其超级视图中删除视图。 但是似乎当动画结束时我添加了removeFromSuperview
调用时,视图根本没有动画,而是立即从屏幕上消失了。
那么,为什么当我添加[[self pickerView] removeFromSuperview];
时没有动画[[self pickerView] removeFromSuperview];
到下面的方法?
- (void) slidePickerOutView
{
[UIView beginAnimations:@"slidePickerOutView" context:nil];
[UIView setAnimationDelegate:self];
[UIView setAnimationBeginsFromCurrentState:YES];
[UIView setAnimationDuration:0.2];
[UIView setAnimationDidStopSelector:@selector(slidePickerOutViewEnded:finished:context:)];
CGRect r = CGRectMake(0, 480, 320, 244);
[[self pickerView] setFrame:r];
[UIView commitAnimations];
}
- (void) slidePickerOutViewEnded:(NSString *)id finished:(BOOL) finished context:(void *) context
{
//Stop observing the 'Done' button
[[self pickerView] removeObserver:self forKeyPath:@"valueSelectDone"];
[[self pickerView] removeObserver:self forKeyPath:@"selectedValue"];
[[self pickerView] removeFromSuperview];
[self setPickerView:nil];
}
好的,我最终找到了导致动画无法开始的原因。 在观察pickerView时,只要一个实例变量的值发生变化,就会通知父视图并启动动画以将pickerview滑出屏幕。 但是由于parentView同时观察了旧值和新值,因此它得到了两次通知,首先是针对旧值,然后是针对新的更改值。 因此,parentView也在紧接彼此之后两次启动了动画,这显然导致了动画完全无法开始。
像这样固定,只需注释掉第一行,该行在每次ValueSelectDone更改值时都将旧值发送给其观察者:
//[self willChangeValueForKey:@"valueSelectDone"];
valueSelectDone = flag;
[self didChangeValueForKey:@"valueSelectDone"];
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