在Swift3中SearchBar的设置

方法1：

UIBarButtonItem.appearance(whenContainedInInstancesOf: [UISearchBar.self]).title = "取消"
UIBarButtonItem.appearance(whenContainedInInstancesOf: [UISearchBar.self]).setTitleTextAttributes([NSForegroundColorAttributeName:UIColor.white], for: .normal)

方法2：(你需要知道取消按钮的Value值)

let cancelButton = searchBar.value(forKey: "cancelButton") as! UIButton
cancelButton.setTitle("取消", for: .normal)
cancelButton.setTitleColor(UIColor.black, for: .normal)

不修改代码，让Cancel按钮显示中文：
在Info.plist文件中修改Localization native development region，默认为en，设置为China

因为在SearchController中的searchBar加载速度比较慢，所以需要延迟让他成为第一响应者

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        self.perform(#selector(ReportViewController.showKeyboard), with: nil, afterDelay: 0.02)

    }
    
    func showKeyboard() {
        self.mySearchController.searchBar.becomeFirstResponder()
    }

修改SearchBar颜色

    // 修改颜色
    func setImageColor(_ color: UIColor, _ size:CGSize) -> UIImage {
        let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()
        context?.setFillColor(color.cgColor)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image!
   }
  searchBar.backgroundImage = setImageColor(UIColor.clear, searchBar.bounds.size)
  searchBar.backgroundColor = UIColor.yourColor