Swift：为键盘抬起视图时视图弹回

Question

我试图在键盘出现时提升视图，但它只是反弹回来。如果我给 CGRectOffset Y 一个正值（向下移动视图），那么它会保持不变。

@IBOutlet weak var PPI: MainTextFields!




    var KbHeight: CGFloat!



    //----------------------------------------------



    func animateTextField(up: Bool) {
        let TFMovement = (up ? -KbHeight : KbHeight)


        UIView.animateWithDuration(0.7, animations: {
            self.view.frame = CGRectOffset(self.view.frame, 0, TFMovement)

        })
    }



    func keyboardWillShow(notification: NSNotification) {
        if let userInfo = notification.userInfo {
            if let keyboardSize = (userInfo[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
                KbHeight = keyboardSize.height
                self.animateTextField(true)
            }

        }

    }


    func keyboardWillHide(notification: NSNotification) {
        self.animateTextField(false)
    }



    //----------------------------------------------


    // Touch Outside Keypad to leave it
    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        self.view.endEditing(true)
    }



    override func viewWillAppear(animated:Bool) {
        super.viewWillAppear(animated)



        // For TextField Movement
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil)
    }


    override func viewWillDisappear(animated: Bool) {
        super.viewWillDisappear(animated)

        //  For TextField Movement
        NSNotificationCenter.defaultCenter().removeObserver(self)
    }


    override func viewDidLoad() {
        super.viewDidLoad()

        PPI.delegate = self

    }

我在 keyboardWillShow 函数中的 CGRectOffset 做错了吗？我是 Swift 的新手，是从教程中学到的，但似乎工作不正常。

Answer 1

我想在 viewController 加载时制作从左到右的背景移动动画。这是我在我的应用程序中所做的：

var backgroundImageView: UIImageView = UIImageView(image: 

UIImage(named: "background.png")!)
self.view.addSubview(backgroundImageView)
self.view.sendSubviewToBack(backgroundImageView)
UIView.animateWithDuration(20.0, animations: {
backgroundImageView.frame = CGRect(x: -700, y: 0, width: backgroundImageView.image!.size.width, height:backgroundImageView.image!.size.height)
})

希望这个例子对您有所帮助:)

尝试使用 CGRect，并给它正 y 值。这样，您将在动画结束时获得这个矩形位置。当小键盘关闭时，将其移回 y 值 0。

Answer 2

原来是因为自动布局约束我不得不上边距，所以需要更改该约束的常量和行：

self.view.frame = CGRectOffset(self.view.frame, 0, TFMovement)

根本不需要。

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