弹出对话框 UIAlertController

双选

//实例化UIAlertController
var av=UIAlertController(title: "💗终极大考验💗",message: "你爱妞妞妈?",preferredStyle: UIAlertControllerStyle.Alert)
//实例化第一个选项
        var act1 = UIAlertAction(title: "爱", style: UIAlertActionStyle.Default){
            (action: UIAlertAction!) -> Void in
            self.lbl1.text="you choosed 爱"  //回调设置lbl1的文本
        }
        //实例化第二个选项
        var act2 = UIAlertAction(title: "超爱", style: UIAlertActionStyle.Destructive){
            (action: UIAlertAction!) -> Void in
            self.lbl1.text="you choosed 超爱"
        }
        //将选项加入对话框
        av.addAction(act1)
        av.addAction(act2)
        
　　　　//显示对话框
        self.presentViewController(av, animated: true, completion: nil)

文本框输入

        var alertController=UIAlertController(title: "请登录", message: "输入登录信息", preferredStyle: UIAlertControllerStyle.Alert)
        alertController.addTextFieldWithConfigurationHandler {
            (textField: UITextField!) -> Void in
            textField.placeholder = "登录"
        }
        alertController.addTextFieldWithConfigurationHandler {
            (textField: UITextField!) -> Void in
            textField.placeholder = "密码"
            textField.secureTextEntry = true
        }
        
        var okAction = UIAlertAction(title: "确定", style: UIAlertActionStyle.Default) {
            (action: UIAlertAction!) -> Void in
            var login = alertController.textFields?.first as UITextField
            var password = alertController.textFields?.last as UITextField
            self.lbl1.text=login.text+password.text
        }
        
        var cancelAction = UIAlertAction(title: "取消", style: UIAlertActionStyle.Default,handler:nil)
        
        alertController.addAction(okAction)
        alertController.addAction(cancelAction)
        
        self.presentViewController(alertController, animated: true, completion: nil)

 带验证的文本框输入

        var alertController=UIAlertController(title: "请登录", message: "输入登录信息", preferredStyle: UIAlertControllerStyle.Alert)
        alertController.addTextFieldWithConfigurationHandler {
            (textField: UITextField!) -> Void in
            //添加用户名输入框
            textField.placeholder = "用户名"
        }
        
        alertController.addTextFieldWithConfigurationHandler {
            (textField: UITextField!) -> Void in
            //添加密码输入框
            textField.placeholder = "密码"
            //不显示明文
            textField.secureTextEntry = true
            //添加一个Observer在更改内容是调用alertTextFieldDidChange函数
            NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("alertTextFieldDidChange:"), name: UITextFieldTextDidChangeNotification, object: textField)
        }
        
        alertController.addTextFieldWithConfigurationHandler{
            (textField: UITextField!) -> Void in
            //为了显示消息 添加一个文本框
            textField.enabled=false
            //设置标志
            textField.tag=1
        }
        
        //创建一个确定按钮
        var okAction = UIAlertAction(title: "确定", style: UIAlertActionStyle.Default) {
            (action: UIAlertAction!) -> Void in
            
            //获取所有文本框
            var tfs=(alertController.textFields?)!
            //获取用户名文本框
            var login = tfs[0] as UITextField
            //获取密码文本框
            var password = tfs[1] as UITextField
            //设置主界面的lbl1文字
            self.lbl1.text=login.text+password.text
            //移除已添加的Observer
            NSNotificationCenter.defaultCenter().removeObserver(self, name: UITextFieldTextDidChangeNotification, object: nil)
        }
        
        var cancelAction = UIAlertAction(title: "取消", style: UIAlertActionStyle.Default){
            (action:UIAlertAction!) -> Void in
            //移除已添加的Observer
            NSNotificationCenter.defaultCenter().removeObserver(self, name: UITextFieldTextDidChangeNotification, object: nil)
        }
        
        //添加按钮
        alertController.addAction(cancelAction)
        alertController.addAction(okAction)
        
        okAction.enabled = false
        self.presentViewController(alertController, animated: true, completion: nil)

    func alertTextFieldDidChange(notification: NSNotification){
        //获取当前的alertController
        var alertController = self.presentedViewController as UIAlertController?
        if (alertController != nil) {
            
            //alertController里所有的文本框
            var tfs=(alertController!.textFields?)!
            //通过索引获取密码文本框
            var passwordTf = tfs[1] as UITextField
            //获取确定按钮
            var okAction = alertController!.actions.last as UIAlertAction
            //取得所有文本框的数量
            var count=tfs.count
            //循环所有文本框
            for i in 0..<count  {
                var tf=tfs[i] as UITextField
                //判断标志
                if(tf.tag==1){
                    //根据密码长度设置消息文本框文本
                    tf.text=(countElements(passwordTf.text) > 2) ? "" : "密码长度必须大于2个字符"
                }
            }
            //设定确定按键是否可用
            okAction.enabled = countElements(passwordTf.text) > 2
        }
    }