如何在不重复代码的情况下在所有控制器中显示警报？ [英] How to show alert in all controllers without repeating the code?

问题描述

我想编写一个函数 alert（）并运行它。但是我想在任何控制器中显示此警报而无需重复代码。

I want to write one function alert() and to run it. But I want to show this alert in any controllers without repeating the code.

例如：我有Presence.swift类，这里有一些条件，例如：

For example: I have Presence.swift class and here I have some condition, as:

if myVar == 1 { // Just for presenting
    runMyAlert()
}

并且在后台 myVar == 1 用户时，无论事实上，他在哪里，在哪个屏幕上，他都会在屏幕上得到警报。

and when in the background myVar == 1 user, regardless of the fact that where he is, on which screen, he gets alert on screen.

如何在不重复代码的情况下做到这一点？我试图在AppDelegate中使它成为：

How can I do it without repeating my code? I tried to make it in AppDelegate as:

func alert(title : String,message : String,buttonTitle : String,window: UIWindow){
    let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)
    alert.addAction(UIAlertAction(title: buttonTitle, style: UIAlertActionStyle.Default, handler: nil))
    window.rootViewController?.presentViewController(alert, animated: true, completion: nil)
}

并将其称为：

if myVar == 1 {
    AppDelegate().alert()
}

推荐答案

在 Swift 您应该了解可以轻松解决问题的协议。您可以创建一个新协议 MyAlert 并为 UIViewController 类设置默认实现。然后只需在需要的地方在视图控制器中继承您的 MyAlert 协议，然后调用该函数即可！

Developing on Swift you should know about protocols which can solve your problem easily. You can create a new protocol MyAlert and make default implementation for UIViewController class. And then just inherit your MyAlert protocol in view controller, where you need it, and call the function!

protocol MyAlert {
    func runMyAlert()
}

extension MyAlert where Self: UIViewController {
    func runMyAlert() {
        let alert = UIAlertController(title: title, message: "message", preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "buttonTitle", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert, animated: true, completion: nil)
    }
}

因此您可以像这样实现并调用它：

So you can implement and call it like that:

class MyViewController: UIViewController, MyAlert {
    override func viewDidLoad() {
        runMyAlert() // for test
    }
}

UPD：

您的案例代码：

protocol MyAlert {
    func runMyAlert()
}

extension MyAlert where Self: UIViewController {
    func runMyAlert() {
        let alert = UIAlertController(title: title, message: "message", preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "buttonTitle", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert, animated: true, completion: nil)
    }
}

class OpenChatsTableViewController: UITableViewController, MyAlert, OneRosterDelegate, BuddyRequestProtocol {
    override func viewDidLoad() {
        runMyAlert()
    }
}

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