快速自定义 UIAlertViewDelegate 不起作用

Question

我是一名 Android 开发人员。

我想在我的代码中使用自定义 UIAlertViewDelegate。

类似演示

import UIKit

class ViewController: UIViewController,UIAlertViewDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int){
        println(buttonIndex)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func onClick1(sender: UIButton) {

        // define here not work
        let delegate = MyUIAlertViewDelegate()

        let alert = UIAlertView(title: "title", message: "message", delegate: delegate, cancelButtonTitle: "cancel", otherButtonTitles: "other","hello")

        alert.alertViewStyle = UIAlertViewStyle.Default

        alert.show()

    }
}

// define here works
// let delegate = MyUIAlertViewDelegate()


class MyUIAlertViewDelegate : UIViewController, UIAlertViewDelegate {
    func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int){
        println("click" + String(buttonIndex))
    }
}

但它不起作用。为什么？

Answer 1

我注意到，当您创建一个名为“alert”的 UIAlertView 时，您将消息设置为消息，出于演示目的，除非消息是具有字符串值的变量，否则这将不起作用。

而且你什么也没有调用alert.show()!它需要被某些东西或某个地方调用，所以在我下面完成的示例中它位于 viewDidAppear 中。

如果您需要此代码完美运行，请复制并粘贴此代码，如有任何问题，请随时提出。

import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

override func viewDidAppear(animated: Bool) {
    alert.show()
}

}

class MyUIAlertViewDelegate : NSObject, UIAlertViewDelegate {
func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int) {
    print("click" + String(buttonIndex))
}
}

let delegate = MyUIAlertViewDelegate()
let alert = UIAlertView(title: "warning", message: "This is a message", delegate: delegate, cancelButtonTitle: "Cancel")