ios - Swift，在键盘后面移动内容不会在关闭后重置

Question

我的一个 VC 中有一个 uiscrollview。在 scrollView 内部，我有多个 TF、按钮等。根据 Apple 文档，我使用下面的代码在调用键盘通知时向上移动 scrollView，以向上推隐藏的文本字段。但是，当我关闭键盘时，scrollView 不会重置或向下移动，它只是停留在“向上移动”的位置。

我是不是漏掉了什么？我有一个名为类的成员变量:

var activeTextField: UITextField!

我是否通过委托(delegate)方法正确地使用了它？

(func registerForKeyboardNotifications() {
    let notificationCenter = NSNotificationCenter.defaultCenter()
    notificationCenter.addObserver(self,
        selector: "keyboardWillBeShown:",
        name: UIKeyboardWillShowNotification,
        object: nil)
    notificationCenter.addObserver(self,
        selector: "keyboardWillBeHidden:",
        name: UIKeyboardWillHideNotification,
        object: nil)
}

func keyboardWillBeShown(sender: NSNotification) {
    let info: NSDictionary = sender.userInfo!
    let value: NSValue = info.valueForKey(UIKeyboardFrameBeginUserInfoKey) as NSValue
    let keyboardSize: CGSize = value.CGRectValue().size
    let contentInsets: UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, keyboardSize.height, 0.0)
    scrollView.contentInset = contentInsets
    scrollView.scrollIndicatorInsets = contentInsets

    // If active text field is hidden by keyboard, scroll it so it's visible
    // Your app might not need or want this behavior.
    var aRect: CGRect = self.view.frame
    aRect.size.height -= keyboardSize.height
    let activeTextFieldRect: CGRect? = activeTextField?.frame
    let activeTextFieldOrigin: CGPoint? = activeTextFieldRect?.origin
    if (!CGRectContainsPoint(aRect, activeTextFieldOrigin!)) {
        scrollView.scrollRectToVisible(activeTextFieldRect!, animated:true)
    }
}

// Called when the UIKeyboardWillHideNotification is sent
func keyboardWillBeHidden(sender: NSNotification) {
    let contentInsets: UIEdgeInsets = UIEdgeInsetsZero
    scrollView.contentInset = contentInsets
    scrollView.scrollIndicatorInsets = contentInsets
}

func textFieldDidBeginEditing(textField: UITextField!) {
    activeTextField = textField
    scrollView.scrollEnabled = true
}

func textFieldDidEndEditing(textField: UITextField!) {
    activeTextField = nil
    scrollView.scrollEnabled = false
}


override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    self.registerForKeyboardNotifications()
}

override func viewDidDisappear(animated: Bool) {
    super.viewWillDisappear(animated)
    NSNotificationCenter.defaultCenter().removeObserver(self)
}

Answer 1

我这样做了并且对我有用。似乎比你的方式容易得多。我为我的项目使用了 UITextView。但它应该与 UITextField 一样工作。 -/+ 25 只是为了显示标题。

func textViewDidBeginEditing(textView: UITextView) {
    myScrollView.setContentOffset(CGPointMake(0, textView.frame.origin.y-25), animated: true)
}

func textViewDidEndEditing(textView: UITextView) {
    myScrollView.setContentOffset(CGPointMake(0, -textView.frame.origin.y+25), animated: true)
}