swift 警告框 - 自定义按钮颜色，图片

1.封装 弹框
http://www.hangge.com/blog/cache/detail_651.html

import UIKit

extension UIAlertController {
    //在指定视图控制器上弹出普通消息提示框
    static func showAlert(message: String, in viewController: UIViewController) {
        let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "确定", style: .cancel))
        viewController.present(alert, animated: true)
    }

    //在根视图控制器上弹出普通消息提示框
    static func showAlert(message: String) {
        if let vc = UIApplication.shared.keyWindow?.rootViewController {
            showAlert(message: message, in: vc)
        }
    }

    //在指定视图控制器上弹出确认框
    static func showConfirm(message: String, in viewController: UIViewController,
                            confirm: ((UIAlertAction)->Void)?) {
        let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "取消", style: .cancel))
        alert.addAction(UIAlertAction(title: "确定", style: .default, handler: confirm))
        viewController.present(alert, animated: true)
    }

    //在根视图控制器上弹出确认框
    static func showConfirm(message: String, confirm: ((UIAlertAction)->Void)?) {
        if let vc = UIApplication.shared.keyWindow?.rootViewController {
            showConfirm(message: message, in: vc, confirm: confirm)
        }
    }
}

　　

2.改变 标题颜色，按钮颜色，等等

https://blog.csdn.net/mo_xiao_mo/article/details/70308099

        let alert = UIAlertController(title: nil, message: "确定要退出登录吗？", preferredStyle: .actionSheet)

        /// 确认
        let sureAction = UIAlertAction(title: "确认", style: UIAlertAction.Style.default) { [weak self](_) in
             self?.requestLoginOut()
        }
        sureAction.setValue(UIColor.init(hexString: "#FF9E3E"), forKey: "_titleTextColor")
        alert.addAction(sureAction)

        //取消操作
        let cancleAction = UIAlertAction(title: "取 消", style: .cancel, handler: nil)
        cancleAction.setValue(UIColor.init(hexString: "#424242"), forKey: "_titleTextColor")
        alert.addAction(cancleAction)
        self.present(alert, animated: true, completion: nil)