iOS swift 如果将RGB颜色赋给UIView的backgroundColor？

Question

使用UIColor的RGB初始化方法没有得到预期的结果
...//
View.backgroundColor = UIColor(red:0.5,green:0.84,blue:0.99,alpha:1.0)
...// 并没有改变颜色
使用了网上的extension也未能解决这个问题，无法改变颜色是因为alertConroller的限制吗？有没有解决的办法呢

具体代码如下：

let alertController = UIAlertController(title: "\n\n\n",
                                        message: "\n\n\n\n", preferredStyle: .alert)

let okAction = UIAlertAction(title: "好的", style: .default, handler: {
    action in
    print("点击了确定")
})

let subview = alertController.view.subviews.first! as UIView
let alertContentView = subview.subviews.first! as UIView
alertContentView.backgroundColor = UIColor()

Answer 1

https://blog.csdn.net/shb2058/article/details/52535054