[英]View is not animated when it's removed from superView
我嘗試在屏幕外動畫后從其超級視圖中刪除視圖。 但是似乎當動畫結束時我添加了removeFromSuperview
調用時,視圖根本沒有動畫,而是立即從屏幕上消失了。
那么,為什么當我添加[[self pickerView] removeFromSuperview];
時沒有動畫[[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,我最終找到了導致動畫無法開始的原因。 在觀察pickerView時,只要一個實例變量的值發生變化,就會通知父視圖並啟動動畫以將pickerview滑出屏幕。 但是由於parentView同時觀察了舊值和新值,因此它得到了兩次通知,首先是針對舊值,然后是針對新的更改值。 因此,parentView也在緊接彼此之后兩次啟動了動畫,這顯然導致了動畫完全無法開始。
像這樣固定,只需注釋掉第一行,該行在每次ValueSelectDone更改值時都將舊值發送給其觀察者:
//[self willChangeValueForKey:@"valueSelectDone"];
valueSelectDone = flag;
[self didChangeValueForKey:@"valueSelectDone"];
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