Swift4中所有视图控制器的连续背景动画

Question

我的第一个视图控制器上有一个无限旋转的图像作为背景，效果很好！

 @IBOutlet var background: UIImageView!

func rotate1(imageView: UIImageView, aCircleTime: Double) {

    let rotationAnimation = CABasicAnimation(keyPath: "transform.rotation")
    rotationAnimation.fromValue = 0.0
    rotationAnimation.toValue = -Double.pi * 2
    rotationAnimation.speed = 0.1
    rotationAnimation.duration = aCircleTime
    rotationAnimation.repeatCount = .infinity
    imageView.layer.add(rotationAnimation, forKey: nil)
}

override func viewWillAppear(_ animated: Bool) {
    rotate1(imageView: background, aCircleTime: Double.pi)
    background.transform = background.transform.rotated(by: CGFloat(Double.pi))
}

（来源：https://github.com/vin20777/infinite-rotate-animation）

当用户在应用程序的各个视图控制器中移动时，是否有可能使旋转继续在后台可见并且在后台不间断？如果是这样，怎么做？

谢谢您的帮助！

Here's a gif of the background animation.