Swift - 告警框（UIAlertView）的用法

class ViewController: UIViewController{
    override func viewDidLoad() {
        super.viewDidLoad()

        let alertView = UIAlertView()
        alertView.title = "系统提示"
        alertView.message = "您确定要离开hangge.com吗？"
        alertView.addButtonWithTitle("取消")
        alertView.addButtonWithTitle("确定")
        alertView.cancelButtonIndex=0
        alertView.delegate=self;
        alertView.show()
    }

    func alertView(alertView:UIAlertView, clickedButtonAtIndex buttonIndex: Int){
        if(buttonIndex==alertView.cancelButtonIndex){
            print("点击了取消")
        }
        else
        {
            print("点击了确认")
        }
    }
}

import UIKit

class ViewController: UIViewController {

    var alertView = UIAlertView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        alertView.title = "系统登录"
        alertView.message = "请输入用户名和密码！"
        alertView.addButtonWithTitle("取消")
        alertView.addButtonWithTitle("确定")
        alertView.cancelButtonIndex=0
        alertView.delegate=self;
        alertView.alertViewStyle = UIAlertViewStyle.LoginAndPasswordInput
        alertView.show()
    }
    
    func alertView(alertView:UIAlertView, clickedButtonAtIndex buttonIndex: Int){
        if(buttonIndex==alertView.cancelButtonIndex){
            print("点击了取消")
        }
        else
        {
            let name = alertView.textFieldAtIndex(0)
            let password = alertView.textFieldAtIndex(1)
            print("用户名是：\(name!.text) 密码是：\(password!.text)")
        }
    }

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