Swift中的链接动画

Question

最近，我制作了一些画面的代码。我想动画脸部来回摇晃。目前我有这个代码。它向右旋转一次，然后向左旋转，然后旋转到原始位置。但是，如果我想让头部无限地来回摇动（旋转浴缸和向前），该怎么办？有可能做一些递归函数来做到这一点吗？

@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
                            )
                        }
                }
                )
            }
    }
    )

}

Answer 1

您可以从最终完成块中调用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)
                            }
                            )
                        }
                }
                )
            }
    }
    )
}

即使这在技术上是递归调用，但由于代码的异步性质，这不是问题。