swift --->iOS 虚拟键盘动态添加视图

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var tfd: UITextField!

    var upView :UIView = UIButton()

    override func viewDidLoad() {

        super.viewDidLoad()

        upView.frame = CGRectMake(0, self.view.frame.size.height , self.view.frame.size.width, 30.0)

        upView.backgroundColor = UIColor.lightGrayColor()

        // 创建“完成”button

        let returnButton = UIButton(frame:CGRectMake(upView.bounds.size.width - 50, 0, 50, 30 ))

        returnButton.backgroundColor = UIColor.lightGrayColor()

        returnButton.setTitle("完成", forState: UIControlState.Normal)

        returnButton.addTarget(self, action: "CancelBackKeyboard", forControlEvents: UIControlEvents.TouchDown)

        upView.addSubview(returnButton)

        self.view.addSubview(upView)

        

        NSNotificationCenter.defaultCenter().addObserver(self, selector: "handleKeyboardDidShow:", name: UIKeyboardWillShowNotification, object: nil)

        NSNotificationCenter.defaultCenter().addObserver(self, selector: "handleKeyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)

        println(upView)

    

    }

    func handleKeyboardDidShow(notification:NSNotification) {

        var info:NSDictionary = notification.userInfo!

        var kbSize = info.objectForKey(UIKeyboardFrameEndUserInfoKey)?.CGRectValue().size

        var distanceToMove = kbSize!.height

        self.adjustKeyboardHeight(distanceToMove)

        

    }

    

    func handleKeyboardWillHide(notification:NSNotification) {

        upView.frame = CGRectMake(0, self.view.frame.size.height, self.view.frame.size.width, 30.0)

        self.view.addSubview(upView)

    }

    

    func adjustKeyboardHeight(height:CGFloat) {

       upView.frame = CGRectMake(0, self.view.frame.size.height - 30 - height, self.view.frame.size.width, 30.0)

        self.view.addSubview(upView)

      

    }

    

    func CancelBackKeyboard() {

        tfd.resignFirstResponder()

    }

    

    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {

        tfd.resignFirstResponder()

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        

    }

}