// 创建动画
        let anim = CABasicAnimation(keyPath: "transform.rotation")
        // 设置动画属性
        anim.toValue = 2 * M_PI
        anim.repeatCount = MAXFLOAT
        anim.duration = 10
        anim.removedOnCompletion = false
        // 将动画添加到图层上
        imageView.layer.addAnimation(anim, forKey: nil)