快速连续旋转动画不那么连续

这是我的代码。目的是连续旋转名为 swirls[l] 的 UIImageView。但是，每次旋转开始/结束之间都会有一个小暂停。我已经浏览了每一个动画教程，但无法弄清楚错误是什么？

let fullRotation = CGFloat(M_PI * 2)

    let duration = 2.0
    let delay = 0.0
    let options = UIViewKeyframeAnimationOptions.Repeat | UIViewKeyframeAnimationOptions.CalculationModeLinear

    UIView.animateKeyframesWithDuration(duration, delay: delay, options: options, animations: {
        UIView.addKeyframeWithRelativeStartTime(0, relativeDuration: 1/3, animations: {
            swirls[l].transform = CGAffineTransformMakeRotation(1/3 * fullRotation)
        })
        UIView.addKeyframeWithRelativeStartTime(1/3, relativeDuration: 1/3, animations: {
            swirls[l].transform = CGAffineTransformMakeRotation(2/3 * fullRotation)
        })
        UIView.addKeyframeWithRelativeStartTime(2/3, relativeDuration: 1/3, animations: {
            swirls[l].transform = CGAffineTransformMakeRotation(3/3 * fullRotation)
        })

        }, completion: {finished in 
    })

编辑：我看到有人建议以前的解决方案可用，但它根本不适用于连续不间断的旋转。对我有用的唯一技巧是我在下面选择的答案。谢谢

尝试以下 swift 4 的扩展。

extension UIView {
    func rotate360Degrees(duration: CFTimeInterval = 3) {
        let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
        rotateAnimation.fromValue = 0.0
        rotateAnimation.toValue = CGFloat(Double.pi * 2)
        rotateAnimation.isRemovedOnCompletion = false
        rotateAnimation.duration = duration
        rotateAnimation.repeatCount=Float.infinity
        self.layer.add(rotateAnimation, forKey: nil)
    }
}

用于开始旋转。

MyView.rotate360Degrees()

和停止。

MyView.layer.removeAllAnimations()

您可以使用UIButton, UILabel还有很多。