ios - 在 iOS 中，如何通过点击 Alert 弹出窗口中的 INSIDE 来关闭 Alert Controller？

Question

有几篇文章介绍了如何通过点击OUTSIDE 弹出窗口来关闭 Alert Controller 弹出窗口。但我想通过点击 INSIDE 弹出窗口来关闭 Alert Controller 弹出窗口。

我在 GitHub 上看到了一些类似于“Toast”的解决方案，但我只想使用 native iOS 代码来实现。

我已经在 SO 周围进行了探索，并获得了在几秒钟后解除警报的代码(例如 Android Toast):

class ViewController: UIViewController {
    let alertController = UIAlertController(title: "Alert", message: "SO Awesome!", preferredStyle: .alert)

    @IBOutlet var alertButton: UIButton!

    @IBAction func displayAlert(_ sender: UIButton) {
        self.present(alertController, animated: true, completion: {
            self.perform(#selector(self.dismissAlert), with: self.alertController, afterDelay: 3)
        })
    }

    // dismiss (close) the alert popup
    @objc func dismissAlert(_ alert: UIAlertController) {
        alert.dismiss(animated: true, completion: nil)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

但是如果我不想等待 3 秒弹出警告关闭怎么办？我希望能够点击弹出警报将其关闭。 (同时保留超时功能)

我发现了一些接近但不完全符合我要求的东西。所以......经过一些工作，我自己回答了这个问题，并在下面包含了一个完整的答案。

Answer 1

我在 SO 上发现的最简单的技巧似乎是添加一个 UIControl，该 UIControl 的操作目标可以在任何触摸事件上关闭 AlertController。但是 UIControl 需要一个框架 CGRect 才能正常运行。

以下是 UIControl 的要点:

let dismissControl = UIControl()

// make the dismissControl execute dismissAlert for all touch events
dismissControl.addTarget(self, action: #selector(self.dismissAlert), for: .allTouchEvents)

// NOTE:  must use the bounds, not the frame for it to work
self.dismissControl.frame = self.alertController.view.bounds

// add the UIControl on top of the UIAlertControl view
self.alertController.view.addSubview(self.dismissControl)

我探索了 4 种不同的可能性:

• 超时 - 几秒后关闭警告窗口(如 Android Toast)
• 在警报窗口外点击(点击警报窗口不会关闭它)
• 点击屏幕上的任意位置将其关闭(在警报窗口上或警报窗口外)
• 点击警报窗口(点击其他任何地方都不会关闭它)

这是一个完整的 ViewController (Xcode 9.2，Swift 4)，它可以处理所有 4 种情况:

//
//  ViewController.swift
//  AlertDemo - Display and dismiss UIAlertControllers with UIControl (no action buttons)
//              (similar to Toast on Android OS)
//
//      4 different ways to close a UIAlertController popup window:
//
//      1) Timeout - dismiss an Alert Window after a number of seconds (like Android Toast)
//      2) Tap outside the Alert Window (tap on Alert Window DOES NOT close it)
//      3) Tap the Alert Window (tap anywhere else DOES NOT close it)
//      4) Tap anywhere on the screen (on Alert Window or outside of it) to close it

//
//  Created by ByteSlinger on 2018-01-19.
//  Copyright © 2018 ByteSlinger. All rights reserved.
//

import UIKit

class ViewController: UIViewController {
    let alertController = UIAlertController(title: "Alert", message: "SO Awesome!", preferredStyle: .alert)
    let timeoutController = UIAlertController(title: "Timeout", message: "That Alert timed out!", preferredStyle: .actionSheet)
    let dismissControl = UIControl()

    @IBOutlet var alertButton1: UIButton!
    @IBOutlet var alertButton2: UIButton!
    @IBOutlet var alertButton3: UIButton!
    @IBOutlet var alertButton4: UIButton!

    // display a modal popup in the middle, wait for timeout to close
    @IBAction func displayAlert1(_ sender: UIButton) {
        alertController.message = "You must wait for this Alert to timeout"

        self.present(alertController, animated: true, completion: {
            self.perform(#selector(self.timeoutAlert), with: self.alertController, afterDelay: 3)
        })
    }

    // display a modal popup in the middle, tap outside popup to close
    @IBAction func displayAlert2(_ sender: UIButton) {
        alertController.message = "Tap outside this Alert to close"

        self.present(alertController, animated: true, completion: {
            self.dismissControl.frame = self.alertController.view.superview?.bounds ?? CGRect.zero

            self.alertController.view.superview?.insertSubview(self.dismissControl, belowSubview: self.alertController.view)

            self.perform(#selector(self.timeoutAlert), with: self.alertController, afterDelay: 3)
        })
    }

    // display a modal popup in the middle, tap on or outside popup to close
    @IBAction func displayAlert3(_ sender: UIButton) {
        alertController.message = "Tap anywhere to close"

        self.present(alertController, animated: true, completion: {
            self.dismissControl.frame = self.alertController.view.superview?.bounds ?? CGRect.zero

            self.alertController.view.superview?.addSubview(self.dismissControl)

            self.perform(#selector(self.timeoutAlert), with: self.alertController, afterDelay: 3)
        })
    }

    // display a modal popup in the middle, tap on popup to close
    @IBAction func displayAlert4(_ sender: UIButton) {
        alertController.message = "Tap on this Alert to close"

        self.present(alertController, animated: true, completion: {
            // important - use bounds:  alertController.view.frame WILL NOT WORK
            self.dismissControl.frame = self.alertController.view.bounds

            self.alertController.view.addSubview(self.dismissControl)

            self.perform(#selector(self.timeoutAlert), with: self.alertController, afterDelay: 3)
        })
    }

    // close the current alert popup (middle) and display the timeout alert (bottom)
    @objc func timeoutAlert(_ alertController: UIAlertController) {
        if (alertController == UIApplication.shared.keyWindow?.rootViewController?.presentedViewController) {
            timeoutController.message = alertController.message!

            alertController.view.willRemoveSubview(self.dismissControl)

            alertController.dismiss(animated: true, completion: {
                self.present(self.timeoutController,animated: true, completion: {
                    self.perform(#selector(self.dismissTimeout), with: self.timeoutController, afterDelay: 2)
                })
            })
        }
    }

    // dimiss (close) the alert popup
    @objc func dismissAlert() {
        // make sure there are no timeoutAlert calls waiting
        NSObject.cancelPreviousPerformRequests(withTarget: self)

        alertController.view.willRemoveSubview(self.dismissControl)

        alertController.dismiss(animated: true, completion: nil)
    }

    // dimiss (close) the timeout popup
    @objc func dismissTimeout(_ alert: UIAlertController) {
        alert.dismiss(animated: true, completion: nil)
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // make the dismissControl execute dismissAlert for all touch events
        dismissControl.addTarget(self, action: #selector(self.dismissAlert), for: .allTouchEvents)

        // make the buttons a little prettier
        alertButton1.layer.cornerRadius = 32
        alertButton2.layer.cornerRadius = 32
        alertButton3.layer.cornerRadius = 32
        alertButton4.layer.cornerRadius = 32
    }
}

要使用它，只需在 IB 中创建 4 个 UIButton 并将它们连接到 @IBOutlet 变量和函数。

注意:我不得不取消执行请求，否则警报有时会被之前的超时取消。 dismissAlert() 中的这一行起到了作用:

NSObject.cancelPreviousPerformRequests(withTarget: self)

这是 GitHub 上的完整 Xcode 项目:AlertDemo

感谢 @Apoc 以及他在这篇文章中对 UIControl 的启发:UIAlertController handle dismiss upon click outside (IPad) .从 UIAlertController 边界设置 UIControl 框架是最终让它工作的原因。