Swift：当键盘显示时向上滚动视图

Question

我有一个scrollView，当显示键盘时我想向上滚动。

我有此错误崩溃当键盘显示：

2014年9月29日14：48：50.738 SWRD [1563：472888] - [swrd.EditPhotoViewController keyboardWasShown]：无法识别的选择发送到实例0x14ed36640

这里是我的代码，有什么不对？

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

在你的代码，keyboardWasShown和keyboardWasHidden各带参数的NSNotification。您需要用冒号终止addObserver中的选择器，以便通过。即，keyboardWasShown和keyboardWasShown:是不同的选择器。

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

Answer 2

见下一个独立的解决方案：

private func startObservingKeyboardEvents() { 
    NSNotificationCenter.defaultCenter().addObserver(self, 
    selector:Selector("keyboardWillShow:"), 
    name:UIKeyboardWillShowNotification, 
    object:nil) 
    NSNotificationCenter.defaultCenter().addObserver(self, 
    selector:Selector("keyboardWillHide:"), 
    name:UIKeyboardWillHideNotification, 
    object:nil) 
} 

private func stopObservingKeyboardEvents() { 
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil) 
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil) 
} 

func keyboardWillShow(notification: NSNotification) { 
    if let userInfo = notification.userInfo { 
    if let keyboardSize: CGSize = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue().size { 
     let contentInset = UIEdgeInsetsMake(0.0, 0.0, keyboardSize.height, 0.0); 
    } 
    } 
} 

func keyboardWillHide(notification: NSNotification) { 
    let contentInset = UIEdgeInsetsZero; 
} 

使用contentInset变量调整内容插图。

Answer 3

对我来说，是需要在代码上面的一些变化：

1 - 首先，你需要把滚动视图在视图中，并设置约束条件是这样的：

这一点很重要你的scrollView比视图更粗糙。

2 - 放置您的TextField和您需要的其他组件。

3 - 链接滚动型到ViewController与@IBOutlet

4 - 代理添加到滚动型：

class ViewController: UIViewController, UITextFieldDelegate,  UIScrollViewDelegate { 
... 

5 - 添加观察者：

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

override func viewWillDisappear(animated: Bool) { 
    self.stopKeyboardObserver() 
} 


private func startKeyboardObserver(){ 
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil) //WillShow and not Did ;) The View will run animated and smooth 
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil) 
} 

private func stopKeyboardObserver() { 
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil) 
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil) 
} 

6 - 添加滚动代码，计算KeyboardSize。

func keyboardWillShow(notification: NSNotification) { 
     if let userInfo = notification.userInfo { 
     if let keyboardSize: CGSize = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue().size { 
      let contentInset = UIEdgeInsetsMake(0.0, 0.0, keyboardSize.height, 0.0); 

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

     self.scrollView.contentOffset = CGPointMake(self.scrollView.contentOffset.x, 0 + keyboardSize.height) //set zero instead self.scrollView.contentOffset.y 

     } 
    } 
} 

func keyboardWillHide(notification: NSNotification) { 
    if let userInfo = notification.userInfo { 
     if let keyboardSize: CGSize = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue().size { 
      let contentInset = UIEdgeInsetsZero; 

     self.scrollView.contentInset = contentInset 
     self.scrollView.scrollIndicatorInsets = contentInset 
     self.scrollView.contentOffset = CGPointMake(self.scrollView.contentOffset.x, self.scrollView.contentOffset.y) 
     } 
    } 
}