ios - CABasicAnimation 不围绕中心缩放

Question

我想同时执行不透明度和缩放效果我的动画工作完美但它的位置不合适。我想在中心执行动画。这是我的代码。

    btn.backgroundColor = UIColor.yellowColor()
    let stroke =  UIColor(red:236.0/255, green:0.0/255, blue:140.0/255, alpha:0.8)
    let pathFrame = CGRectMake(24, 13, btn.bounds.size.height/2, btn.bounds.size.height/2)

    let circleShape1 = CAShapeLayer()
    circleShape1.path = UIBezierPath(roundedRect: pathFrame, cornerRadius: btn.bounds.size.height/2).CGPath
    circleShape1.position = CGPoint(x: 2, y: 2)
    circleShape1.fillColor = stroke.CGColor
    circleShape1.opacity = 0

    btn.layer.addSublayer(circleShape1)

    circleShape1.anchorPoint = CGPoint(x: 0.5, y: 0.5)

    let scaleAnimation = CABasicAnimation(keyPath: "transform.scale")
    scaleAnimation.fromValue = NSValue(CATransform3D: CATransform3DIdentity)
    scaleAnimation.toValue = NSValue(CATransform3D: CATransform3DMakeScale(2.0, 2.0, 1))

    let alphaAnimation = CABasicAnimation(keyPath: "opacity")
    alphaAnimation.fromValue = 1
    alphaAnimation.toValue = 0

    CATransaction.begin()
    let animation = CAAnimationGroup()
    animation.animations = [scaleAnimation, alphaAnimation]
    animation.duration = 1.5
    animation.repeatCount = .infinity
    animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
    circleShape1.addAnimation(animation, forKey:"Ripple")
    CATransaction.commit()

Answer 1

问题是您没有正确处理框架。你说:

 let circleShape1 = CAShapeLayer()

但是你忘了给circleShape1一个框架!因此，它的大小为零，当你为它设置动画时会发生非常奇怪的事情。您在下一行的工作应该是为 circleShape1 分配一个框架。示例:

circleShape1.frame = pathFrame

这可能是也可能不是正确的框架；可能不是。但你需要弄清楚这一点。

然后，您需要根据形状层的边界修复贝塞尔路径的框架:

circleShape1.path = UIBezierPath(roundedRect: circleShape1.bounds // ...