CABasicAnimation如何获取当前的旋转角度

Question

我的CABasicAnimation存在一些问题。它类似于该帖子：CABasicAnimation rotate returns to original position

所以，我有uiimageview在touchMove中旋转。在touchEnd调用方法做“的动画惯性”：

-(void)animationRotation: (float)beginValue 
{ 
    CABasicAnimation *anim; 
    anim = [CABasicAnimation animationWithKeyPath:@"transform.rotation"]; 
    anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut]; 
    anim.duration = 0.5; 
    anim.repeatCount = 1; 

    anim.fillMode = kCAFillModeForwards; 
    anim.fromValue = [NSNumber numberWithFloat:beginValue]; 
    [anim setDelegate:self];  

    anim.toValue = [NSNumber numberWithFloat:(360*M_PI/180 + beginValue)]; 
    [appleView.layer addAnimation:anim forKey:@"transform"]; 

    CGAffineTransform rot = CGAffineTransformMakeRotation(360*M_PI/180 + beginValue); 
    appleView.transform = rot; 
} 

这部动画工作正常，但如果我调用touchBegan animationRotation结束前，旋转角度为beginValue。我需要阴极电流旋转角度。作为一个实验，我宣布方法

-(vod) animationDidStop:(CAAnimation *)anim finished:(BOOL)flag 
{ 
     NSLog(@"Animation finished!"); 
} 

和它似乎工作。但我不知道如何在animationDidStop中为我的UIImageView获取角度值或CGAffineTransform值。 这甚至有可能吗？谢谢。

Answer 1

您应该使用presentationLayer方法在飞行动画期间获取图层属性。

使你的代码应该是这样的，

#define RADIANS_TO_DEGREES(__ANGLE__) ((__ANGLE__)/(float)M_PI * 180.0f) 

    -(void)animationRotation: (float)beginValue 
    { 
     CABasicAnimation *anim; 
     anim = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"]; 
     anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut]; 
     anim.duration = 0.5; 
     anim.repeatCount = 1; 

     anim.fillMode = kCAFillModeForwards; 
     anim.fromValue = [NSNumber numberWithFloat:beginValue]; 
     [anim setDelegate:self];  



    //get current layer angle during animation in flight 
     CALayer *currentLayer = (CALayer *)[appleView.layer presentationLayer];  
     float currentAngle = [(NSNumber *)[currentLayer valueForKeyPath:@"transform.rotation.z"] floatValue]; 
     currentAngle = roundf(RADIANS_TO_DEGREES(currentAngle));   

     NSLog(@"current angle: %f",currentAngle); 



     anim.toValue = [NSNumber numberWithFloat:(360*M_PI/180 + beginValue)]; 
     [appleView.layer addAnimation:anim forKey:@"transform"]; 

     CGAffineTransform rot = CGAffineTransformMakeRotation(360*M_PI/180 + beginValue); 
     appleView.transform = rot; 
    }