我如何使用MonoTouch为UIButton Alpha属性设置动画

Question

我有一个简单的带有Alpha属性的UIButton，我想从1.0f动画到0.0f，然后回到1.0f。这基本上是对TouchDown的回应。

此外，有什么特别的我需要做的，如果我打来的例程不在主线程（在ThreadPool上调用的异步委托）？

我应该使用CAAnimation吗？

谢谢！

Answer 1

除非有人管了一个单声道的方式来做到这一点，我说的使用：

- (void) pulseButton { 
    button.alpha = 0.0; 
    [UIView beginAnimations:nil context:button]; { 
     [UIView setAnimationDelegate:self]; 
     [UIView setAnimationDidStopSelector:@selector(makeVisibleAgain:finished:context:)]; 
     [UIView setAnimationCurve:UIViewAnimationCurveEaseOut]; 
     [UIView setAnimationDuration:0.50]; 
     button.alpha = 0.0; 
    } [UIView commitAnimations]; 
} 
- (void)makeVisibleAgain:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context 
{ 
    UIButton *button = ((UIButton *) context); 
    [UIView beginAnimations:nil context:nil]; { 
     [UIView setAnimationDelegate:nil]; 
     [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; 
     [UIView setAnimationDuration:0.5]; 
     button.alpha = 1.0; 
    } [UIView commitAnimations]; 

} 

Answer 2

这是非常简单的：

UIView button; 

public void fadeButtonInAndOut() 
{ 
    UIView.BeginAnimations("fadeOut"); 
    UIView.SetAnimationDelegate(this); 
    UIView.SetAnimationDidStopSelector(new Selector("fadeOutDidFinish")); 
    UIView.SetAnimationDuration(0.5f); 
    button.Alpha = 0.0f; 
    UIView.CommitAnimations(); 
} 

[Export("fadeOutDidFinish")] 
public void FadeOutDidFinish() 
{ 
    UIView.BeginAnimations("fadeIn"); 
    UIView.SetAnimationDuration(0.5f); 
    button.Alpha = 1.0f; 
    UIView.CommitAnimations(); 
} 

Answer 3

谢谢你的iPhone后置代号。

第二个答案是使用全局变量并跳过回调的参数。 这是我今天根据第一个答案想出来的。

private void BeginPulse (Button button) 
{ 
    UIView.BeginAnimations (button+"fadeIn", button.Handle); 
    UIView.SetAnimationDelegate (this); 
    UIView.SetAnimationDidStopSelector (new MonoTouch.ObjCRuntime.Selector ("makeVisibleAgain:finished:context:")); 
    UIView.SetAnimationCurve(UIViewAnimationCurve.EaseOut); 
    UIView.SetAnimationDuration (0.5); 
    button.Alpha = 0.25f; 
    UIView.CommitAnimations(); 
} 

[Export ("makeVisibleAgain:finished:context:")] 
private void EndPulse (NSString animationId, NSNumber finished, UIButton button) 
{ 
    UIView.BeginAnimations (null, System.IntPtr.Zero); 
    UIView.SetAnimationDelegate (this); 
    UIView.SetAnimationCurve (UIViewAnimationCurve.EaseIn); 
    UIView.SetAnimationDuration (0.5); 
    button.Alpha = 1; 
    UIView.CommitAnimations(); 
}