无法更改搜索栏背景颜色

我有一个搜索栏：

let searchBar:UISearchBar = UISearchBar(frame: CGRectMake((searchView.frame.width - UIScreen.mainScreen().bounds.width / 1.6) / 2, 0, UIScreen.mainScreen().bounds.width / 1.6, 24))

我想更改文本输入部分的背景颜色。为此我尝试过：

searchBar.barTintColor = UIColor(red: 0/255, green: 74/255, blue: 103/255, alpha: 1)

searchBar.backgroundColor = UIColor.redColor()

但这两种变体都不起作用。如何更改 UISearchBar textInput 部分的背景颜色以及我做错了什么？

就像@aliamcami一样，之前的所有答案都没有像我预期的那样工作，要么答案对我不起作用，要么它有效，但它需要太多“虚拟”代码。所以我分享另一个答案Swift 4简化逻辑：

for textField in searchController.searchBar.subviews.first!.subviews where textField is UITextField {
    textField.subviews.first?.backgroundColor = .white
    textField.subviews.first?.layer.cornerRadius = 10.5 //I set 10.5 because is approximately the system value
    textField.subviews.first?.layer.masksToBounds = true
    //Continue changing more properties...
}

textField.subviews.first是“_UISearchBarSearchFieldBackgroundView”子视图，它在后面添加视觉效果UIFieldEditor.

Edited

经过一些开发和许多错误后，我完成了这个elegant解决方案（我确信苹果不会乐意批准，但我不知道），适用于iOS 10 to iOS 12:

if let textField = searchBar.value(forKey: "searchField") as? UITextField {
    textField.backgroundColor = myColor
    //textField.font = myFont
    //textField.textColor = myTextColor
    //textField.tintColor = myTintColor
    // And so on...
    
    let backgroundView = textField.subviews.first
    if #available(iOS 11.0, *) { // If `searchController` is in `navigationItem`
        backgroundView?.backgroundColor = UIColor.white.withAlphaComponent(0.3) //Or any transparent color that matches with the `navigationBar color`
        backgroundView?.subviews.forEach({ $0.removeFromSuperview() }) // Fixes an UI bug when searchBar appears or hides when scrolling
    }
    backgroundView?.layer.cornerRadius = 10.5
    backgroundView?.layer.masksToBounds = true
    //Continue changing more properties...
}

当。。。的时候searchBar在里面tableHeaderView上面的代码可以在中调用viewWillAppear，但如果它在navigationItem在 iOS 11 及更高版本上，应该调用它viewDidAppear.