使用 CAKeyframeAnimation 反转 UIImageView 的旋转

Question

我正在使用以下代码无限旋转图像，旋转是顺时针的，但我还需要它每旋转 1-2 圈就逆时针反向旋转，然后再回到顺时针方向，如何让它工作？

    /// Image Rotation - CAKeyframeAnimation
func rotate(imageView: UIImageView, rotationSpeed: Double) {

    let animation = CAKeyframeAnimation(keyPath: "transform.rotation.z")

    animation.duration = rotationSpeed
    animation.fillMode = CAMediaTimingFillMode.forwards
    animation.repeatCount = .infinity
    animation.values = [0, Double.pi/2, Double.pi, Double.pi*3/2, Double.pi*2]

    /// Percentage of each key frame
    let moments = [NSNumber(value: 0.0), NSNumber(value: 0.1),
                   NSNumber(value: 0.3), NSNumber(value: 0.8), NSNumber(value: 1.0)]
    animation.keyTimes = moments

    imageView.layer.add(animation, forKey: "rotate")
}

Answer 1

设置animation.autoreverses = true，会反转一个动画。

Answer 2

逆时针旋转，可以这样做：

self.imageView?.transform = CGAffineTransform(rotationAngle: -2*CGFloat.pi)

使用 CAKeyframeAnimation 反转 UIImageView 的旋转

Reverse the rotation of UIImageView using CAKeyframeAnimation

cakeyframeanimation

ios

swift