ios - swift : scroll the view up when keyboard shows

Question

我有一个 scrollView，我想在显示键盘时向上滚动。

当键盘显示时，我因此错误而崩溃:

2014-09-29 14:48:50.738 swrd[1563:472888] -[swrd.EditPhotoViewController keyboardWasShown]:无法识别的选择器发送到实例 0x14ed36640

这是我的代码，有什么问题吗？:

   func registerForKeyboardNotifications ()-> Void   {

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWasShown", name: UIKeyboardDidShowNotification, object: nil)

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


}

func deregisterFromKeyboardNotifications () -> Void {
    let center:  NSNotificationCenter = NSNotificationCenter.defaultCenter()
    center.removeObserver(self, name: UIKeyboardDidHideNotification, object: nil)
    center.removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)


}


 func keyboardWasShown (notification: NSNotification) {

    let info : NSDictionary = notification.userInfo!
    let keyboardSize = info.objectForKey(UIKeyboardFrameBeginUserInfoKey)?.frame

    let insets: UIEdgeInsets = UIEdgeInsetsMake(self.scrollView.contentInset.top, 0, keyboardSize!.height, 0)

    self.scrollView.contentInset = insets
    self.scrollView.scrollIndicatorInsets = insets

    self.scrollView.contentOffset = CGPointMake(self.scrollView.contentOffset.x, self.scrollView.contentOffset.y + keyboardSize!.height)

}

func keyboardWillBeHidden (notification: NSNotification) {

    let info : NSDictionary = notification.userInfo!
    let keyboardSize = info.objectForKey(UIKeyboardFrameBeginUserInfoKey)?.frame

    let insets: UIEdgeInsets = UIEdgeInsetsMake(self.scrollView.contentInset.top, 0, keyboardSize!.height, 0)

    self.scrollView.contentInset = insets
    self.scrollView.scrollIndicatorInsets = insets



}


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



   self.registerForKeyboardNotifications()

}

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

    self.deregisterFromKeyboardNotifications()

}

Answer 1

在您的代码中，keyboardWasShown 和 keyboardWasHidden 各有一个参数，NSNotification。您需要用冒号终止 addObserver 中的选择器，以便它通过。即，keyboardWasShown 和 keyboardWasShown: 是不同的选择器。

NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWasShown:", name: UIKeyboardDidShowNotification, object: nil)