Ios 在Swift中链接动画

最近，我做了一些代码来画一张脸。我想给这张脸做动画，让它前后摇晃。目前我有这个代码。它向右旋转一次，然后向左旋转更多，然后旋转到原始位置。然而，如果我想让头无限地前后摇晃（来回旋转浴缸），会怎么样。是否可以使用某种递归函数来实现这一点

@IBAction func shakeHead(_ sender: UITapGestureRecognizer) {

    UIView.animate(
        withDuration: 0.5,
        animations: {
            self.faceView.transform = self.faceView.transform.rotated(by: self.shakeAngle)
    },
        completion:{ finished in
            if(finished){
                UIView.animate(
                    withDuration: 0.5,
                    animations: {
                        self.faceView.transform = self.faceView.transform.rotated(by: -(self.shakeAngle)*2)
                },
                    completion:{ finished in
                        if(finished){
                            UIView.animate(
                                withDuration: 0.5,
                                animations: {
                                    self.faceView.transform = self.faceView.transform.rotated(by: self.shakeAngle)
                            },
                                completion: nil
                            )
                        }
                }
                )
            }
    }
    )

}

---

您可以从最终完成块调用

shakeHead

@IBAction func shakeHead(_ sender: UITapGestureRecognizer) {

    UIView.animate(
        withDuration: 0.5,
        animations: {
            self.faceView.transform = self.faceView.transform.rotated(by: self.shakeAngle)
    },
        completion:{ finished in
            if(finished){
                UIView.animate(
                    withDuration: 0.5,
                    animations: {
                        self.faceView.transform = self.faceView.transform.rotated(by: -(self.shakeAngle)*2)
                },
                    completion:{ finished in
                        if(finished){
                            UIView.animate(
                                withDuration: 0.5,
                                animations: {
                                    self.faceView.transform = self.faceView.transform.rotated(by: self.shakeAngle)
                            },
                                completion: { finished in
                                    shakeHead(sender)
                            }
                            )
                        }
                }
                )
            }
    }
    )
}

尽管这在技术上是一个递归调用，但由于代码的异步性质，这并不是一个问题