CABasicAnimation Position.Y

Question

我只是想我的动画中的UIButton使用此功能的位置：

CABasicAnimation *moveUp; 
    moveUp   = [CABasicAnimation animationWithKeyPath:@"position.y"]; 
    moveUp.fromValue = [NSNumber numberWithFloat:self.retestBTN.frame.origin.y]; 
    moveUp.toValue = [NSNumber numberWithFloat:self.retestBTN.frame.origin.y - 50]; 
    moveUp.duration = 1.0; 
    moveUp.removedOnCompletion = NO; 
    moveUp.fillMode = kCAFillModeBoth; 
    moveUp.delegate = self; 
    [[retestBTN layer] addAnimation:moveUp forKey:@"y"]; 

，然后我想在以后的动画回来那段时间与功能：

CABasicAnimation *moveDown; 
moveDown   = [CABasicAnimation animationWithKeyPath:@"position.y"]; 
moveDown.fromValue = [NSNumber numberWithFloat:self.retestBTN.frame.origin.y]; 
moveDown.toValue = [NSNumber numberWithFloat:self.retestBTN.frame.origin.y + 50]; 
moveDown.duration = 1.0; 
moveDown.removedOnCompletion = NO; 
moveDown.fillMode = kCAFillModeForwards; 
[[retestBTN layer] addAnimation:moveDown forKey:@"y"]; 

但是，这不能正常工作，我的UIButton去奇怪的位置...

Answer 1

通过使用CAAnimation你只是动画图层。而且您实际上并没有更改对象的modelLayer，只有presentationLayer因为您只创建动画并且从未实际更改图层的position属性。这意味着该按钮从未实际移动，只是它在屏幕上的移动位置。

如果你的按钮是一个UIButton，那么它仍然会在视图所在的位置接受触摸，而不是图层所在的位置。您可以动画任何视图更容易使用的UIKit像这样：

[UIView animateWithDuration:1.0 
         delay:0.0 
        options:UIViewAnimationOptionCurveEaseInOut 
       animations:^{ 
        CGRect frame = self.retestBTN.frame; 
        frame.origin.y -= 50; 
        self.retestBTN.frame = frame; 
       } 
       completion:^(BOOL finished){ 
        //callback code goes here 
       }]; 

Answer 2

你面临的问题是，位置是不一样的原点。

无论如何，你正在做的位置的相对动画所以，如果你跳过toValue和fromValue，转而使用byValue属性（与相对变化），它会更容易。您的代码应该是这样的：

CABasicAnimation *moveUp; 
moveUp   = [CABasicAnimation animationWithKeyPath:@"position.y"];  
moveUp.byValue = @(-50.0f); // or [NSNumber numberWithFloat:-50.0f] if you really need to 
moveUp.duration = 1.0; 
moveUp.removedOnCompletion = NO; 
moveUp.fillMode = kCAFillModeBoth; 
moveUp.delegate = self; 
[[retestBTN layer] addAnimation:moveUp forKey:@"y"]; 

和

CABasicAnimation *moveDown; 
moveDown   = [CABasicAnimation animationWithKeyPath:@"position.y"]; 
moveDown.byValue = @(50.0f); // or [NSNumber numberWithFloat:50.0f] if you really need to 
moveDown.duration = 1.0; 
moveDown.removedOnCompletion = NO; 
moveDown.fillMode = kCAFillModeForwards; 
[[retestBTN layer] addAnimation:moveDown forKey:@"y"];