animation - 核心动画 : why can I not composite two animations?

Question

我正在尝试为轮子制作动画

当手指停留 > 0.1 秒时，轮子“弹出”，即我将 Scale 从 1.0 设置为 1.2。

当手指移动时，轮子会随之转动(只有弹出时才有效)。

但我遇到了一个问题:它一开始旋转，比例就缩小回 1.0。

- (void) spin: (Direction) direction
{
 float thetaOld = thetaWheel;

 float k = (direction == AntiClockwise) ? -1 : 1;
 float t = 2 * M_PI * ( k / 12.0 );
 thetaWheel += t;

 CABasicAnimation * anim = [CABasicAnimation animationWithKeyPath:@"transform"];

 anim.fromValue = [NSNumber numberWithDouble: thetaOld];
 anim.toValue = [NSNumber numberWithDouble: thetaWheel];

 anim.valueFunction = [CAValueFunction functionWithName: kCAValueFunctionRotateZ];

 anim.timingFunction = [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionEaseInEaseOut]; 

 anim.duration = 0.1f;
 anim.fillMode = kCAFillModeForwards;
 anim.removedOnCompletion = NO;

 [self.wheelLayer addAnimation: anim forKey:@"transform"];
}

- (void) popOut
{
 CABasicAnimation * anim = [CABasicAnimation animationWithKeyPath:@"transform.scale"];

 anim.fromValue = [NSNumber numberWithDouble: 1.0];
 anim.toValue = [NSNumber numberWithDouble: 1.2];

 anim.timingFunction = [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionEaseInEaseOut]; 

 anim.duration = 0.25f;
 anim.fillMode = kCAFillModeForwards;
 anim.removedOnCompletion = NO;

 [self.wheelLayer addAnimation: anim forKey:@"transform.scale"];
}

// doesnt get used yet
- (void) popBack
{
 CABasicAnimation * anim = [CABasicAnimation animationWithKeyPath:@"transform.scale"];

 anim.fromValue = [NSNumber numberWithDouble: 1.2];
 anim.toValue = [NSNumber numberWithDouble: 1.0];

 anim.timingFunction = [CAMediaTimingFunction functionWithName: kCAMediaTimingFunctionEaseInEaseOut]; 

 anim.duration = 0.1f;
 anim.fillMode = kCAFillModeForwards;
 anim.removedOnCompletion = NO;

 [self.wheelLayer addAnimation: anim forKey:@"transform.scale"];
}

最后一个例程暂时用不到!所以我看不出是什么将比例缩小回 1...

看起来第二个动画以某种方式覆盖了第一个...

如何正确地做到这一点？

Answer 1

我猜想(尚未测试)在“变换”keyPath 的动画中应用的图层变换会覆盖您在缩放动画中应用的变换。

对于旋转，请尝试使用带有 transform.rotation.z 键路径的动画(在这种情况下您不需要设置 valueFunction)