Swift 提示框(keyWindow)

近日在学习Swift的过程中用到了提示框，按照原来OC的方法在keyWindow上推出提示框的时候，被提示

'keyWindow' was deprecated in iOS 13.0: Should not be used for applications that support multiple scenes as it returns a key window across all connected scenes

iOS13以后原来的keyWindow方法就不能使用了，那么我们应该怎么获取keyWindow呢？

1.解决方法

方法一：

UIApplication.shared.windows.filter {$0.isKeyWindow}.first

或者

UIApplication.shared.windows.first {$0.isKeyWindow}

方法二：

let keyWindow = UIApplication.shared.connectedScenes
            .filter({$0.activationState == .foregroundActive})
            .map({$0 as? UIWindowScene})
            .compactMap({$0})
            .first?.windows
            .filter({$0.isKeyWindow}).first

2.另外附上自己封装的提示框，仅供参考

import Foundation
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)
        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) {
        let keyWindow = UIApplication.shared.windows.filter {$0.isKeyWindow}.first        
        if let vc = 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, handler: nil))
        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)?) {
        let keyWindow = UIApplication.shared.windows.filter {$0.isKeyWindow}.first
        if let vc = keyWindow?.rootViewController {
            showConfirm(message: message, in: vc, confirm: confirm)
        }
    }
    
    /// 在指定视图控制器上提示警告信息
    static func showWarning(_ message: String, in viewController: UIViewController) {
        let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
        viewController.present(alert, animated: true, completion: nil)
        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
            alert.dismiss(animated: true, completion: nil)
        }
    }
    /// 在根定视图控制器上提示警告信息
    static func showWarning(_ message: String) {
        let keyWindow = UIApplication.shared.connectedScenes
        .filter({$0.activationState == .foregroundActive})
        .map({$0 as? UIWindowScene})
        .compactMap({$0})
        .first?.windows
        .filter({$0.isKeyWindow}).first
        if let vc = keyWindow?.rootViewController {
            showWarning(message, in: vc)
        }
    }
}