ios - CAShapeLayer路径动画——缩小一个圆

Question

我正在尝试缩小圆形 CAShapeLayer，但使用关键路径“路径”似乎不起作用。

CGPathRef startPath = [UIBezierPath bezierPathWithOvalInRect:startRect].CGPath;
CGPathRef endPath   = [UIBezierPath bezierPathWithOvalInRect:CGRectInset(startRect, 15, 15)].CGPath;

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"path"];
animation.duration          = 1.0;
animation.fromValue         = (__bridge id)startPath;
animation.toValue           = (__bridge id)endPath;
animation.autoreverses      = YES;
animation.repeatCount       = CGFLOAT_MAX;
animation.timingFunction    = [CAMediaTimingFunction functionWithControlPoints:0.6 :0.3 :0.8 :0.45];

//circleLayer is a CAShapeLayer
[self.circleLayer addAnimation:animation forKey:@"pathAnimation"];

我认为我一定误解了路径动画的工作原理，因为如果我尝试对不透明度或变换进行动画处理，几乎相同的代码似乎可以正常工作。

有什么想法吗？

Answer 1

我最近遇到了同样的问题，最终通过创建圆来解决它，然后为比例 CGAffineTransform 设置动画。在图层为圆形的 View 中，我简单地使用了

CGAffineTransform transform = CGAffineTransformIdentity;
transform = CGAffineTransformScale(transform, scaleX, scaleY);

[UIView animateWithDuration: 0.5 animations: ^{
    self.transform = transform;
}];

希望这对您有所帮助!