ios - 在 Swift 3 中设置动画背景颜色

Question

我目前有一个静态背景色:

self.backgroundColor = UIColor(red: 0.0, green: 0.0, blue: 1.0, alpha: 1.0)

我如何编写代码以在设定的秒数(例如每种颜色 5 秒)内创建一系列动画颜色，然后返回到颜色循环的开头？

我尝试了以下...

self.backgroundColor = UIColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0)
UIView.animate(withDuration: 5.0, animations: { () -> Void in
    self.backgroundColor = UIColor(red: 0.0, green: 1.0, blue: 0.0, alpha: 1.0);
    self.backgroundColor = UIColor(red: 0.0, green: 0.0, blue: 1.0, alpha: 1.0)
})

...但这只是停留在最后一种蓝色。

Answer 1

必须制作嵌套动画

    self.backgroundColor = UIColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0)
    UIView.animate(withDuration: 5.0, animations: { () -> Void in
        self.backgroundColor = UIColor(red: 0.0, green: 1.0, blue: 0.0, alpha: 1.0);
    },
     completion: { finished in
        UIView.animate(withDuration: 5.0, animations: { () -> Void in
            self.backgroundColor = UIColor(red: 0.0, green: 0.0, blue: 1.0, alpha: 1.0)
        }, completion: { finished in
            //other color do the same
        })

    })