使用CABasicAnimation
keyPath = 'transform.rotation.z'
一圈一秒.圈数设置无限大.
增加到控件的layer上面.
private func showLoading(){
loadingImage.isHidden = false
let basicAni: CABasicAnimation = CABasicAnimation()
basicAni.keyPath = "transform.rotation.z"
basicAni.fromValue = 0
basicAni.toValue = -M_PI * 2
basicAni.duration = 1
basicAni.repeatCount = MAXFLOAT
self.loadingImage.layer.add(basicAni, forKey: nil)
}
