如何在Swift Playgrounds中获得弹出对话框

Question

我想知道如何在Swift Playgrounds中弹出一个对话框（是的，必须在Playgrounds中）我尝试了以下代码（直接来自AppleDevs网站）

但是，无论我尝试什么，self标签总是会抛出错误。谁能帮我这个？

import UIKit
let alert = UIAlertController(title: "My Alert", message: "This is an alert.", preferredStyle: .alert) 
alert.addAction(UIAlertAction(title: NSLocalizedString("OK", comment: "Default action"), style: .default, handler: { _ in 
    NSLog("The \"OK\" alert occured.")
}))
self.present(alert, animated: true, completion: nil)

Answer 1

需要从视图控制器呈现警报。而不是意味着它将出现在助理编辑器内的模拟器中：

例：

import UIKit
import PlaygroundSupport

import UIKit
let alert = UIAlertController(title: "My Alert", message: "This is an alert.", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: NSLocalizedString("OK", comment: "Default action"), style: .default, handler: { _ in
    NSLog("The \"OK\" alert occured.")
}))
let v = UIViewController()
PlaygroundPage.current.liveView = v
v.present(alert, animated: true, completion: nil)