ios 键盘上的 NSNotificationCenter Swift 3.0 显示和隐藏

NSNotificationCenter Swift 3.0 on keyboard show and hide

提问by Dhwanit Zaveri

I am trying to run a function when the keyboard shows and disappears and have the following code:

我试图在键盘显示和消失时运行一个函数，并具有以下代码：

let notificationCenter = NotificationCenter.default
notificationCenter.addObserver(self, selector: #selector(ViewController.keyBoardUp(Notification :)), name:  NSNotification.Name.UIKeyboardWillShow, object: nil)

And the function keyBoardUpbelow:

和keyBoardUp下面的功能：

func keyBoardUp( Notification: NSNotification){
    print("HELLO")
}

However the function doesn't print to the console when the keyboard shows. Help would be greatly appreciated

但是，当键盘显示时，该函数不会打印到控制台。帮助将不胜感激

回答by Vandana

Swift 3:

斯威夫特 3：

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillShow), name: Notification.Name.UIKeyboardWillShow, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillHide), name: Notification.Name.UIKeyboardWillHide, object: nil)

}

func keyboardWillShow(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        print("notification: Keyboard will show")
        if self.view.frame.origin.y == 0{
            self.view.frame.origin.y -= keyboardSize.height
        }
    }

}

func keyboardWillHide(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y != 0 {
            self.view.frame.origin.y += keyboardSize.height
        }
    }
}

Swift 4.2.1:

斯威夫特 4.2.1：

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)

@objc fileprivate func keyboardWillShow(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        // Do something with size
    }
}

@objc fileprivate func keyboardWillHide(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        // Do something with size
    }
}

Swift 4.2+

斯威夫特 4.2+

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)

}

@objc func keyboardWillShow(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y == 0{
            self.view.frame.origin.y -= keyboardSize.height
        }
    }

}

@objc func keyboardWillHide(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y != 0 {
            self.view.frame.origin.y += keyboardSize.height
        }
    }
}

回答by Rakesha Shastri

Swift 4.2+

斯威夫特 4.2+

@vandana'sanswer updated to reflect changesto native Notifications in Swift 4.2.

@vandana 的答案已更新，以反映Swift 4.2 中对本机通知的更改。

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)

}

@objc func keyboardWillShow(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        print("notification: Keyboard will show")
        if self.view.frame.origin.y == 0{
            self.view.frame.origin.y -= keyboardSize.height
        }
    }

}

@objc func keyboardWillHide(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y != 0 {
            self.view.frame.origin.y += keyboardSize.height
        }
    }
}

Also, you need to use UIKeyboardFrameEndUserInfoKeyto account for safeAreaInsetchanges introduced with iOS 11.

此外，您需要使用UIKeyboardFrameEndUserInfoKey来说明iOS 11safeAreaInset引入的更改。

回答by Pankaj K.

set keyboard notification observer in

设置键盘通知观察者

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
    NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardNotification(notification:)), name: NSNotification.Name.UIKeyboardDidShow, object: nil)
}

and in your function handle it

并在您的函数中处理它

func keyboardNotification(notification: NSNotification) {
  print("keyboard displayed!!")
}

hope this will help you.

希望这会帮助你。

回答by blackjacx

Swift 4.X / 5

斯威夫特 4.X / 5

I like the inline, block-based approach which is available for a long time already! You can read more about the parameters of addObserver(...)here.

我喜欢内联的、基于块的方法，它已经存在很长时间了！您可以在addObserver(...)此处阅读有关参数的更多信息。

Some advantages of this approach are:

这种方法的一些优点是：

• you don't need to use the @objc keyword
• you write your callback code at the same location where you setup your observer

• 你不需要使用@objc 关键字
• 您在设置观察者的同一位置编写回调代码

Important:Call NotificationCenter.default.removeObserver(observer)in the deinitof the object where you set register the observer (often a view controller).

重要提示：呼叫NotificationCenter.default.removeObserver(observer)在deinit你设置注册观察者（通常是一个视图控制器）的对象。

let center = NotificationCenter.default

let keyboardWillShowObserver: NSObjectProtocol = center.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: nil) { (notification) in
    guard let value = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue else { return }
    let height = value.cgRectValue.height

    // use the height of the keyboard to layout your UI so the prt currently in
    // foxus remains visible
}

let keyboardWillHideObserver: NSObjectProtocol = center.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: nil) { (notification) in

    // restore the layout of your UI before the keyboard has been shown
}

回答by Alessandro Ornano

Swift 4.2

斯威夫特 4.2

This version works both on the iPhone 5 and the iPhone X. It works very well if you respect the safe area during your constraints settings.

此版本适用于 iPhone 5 和 iPhone X。如果您在约束设置期间尊重安全区域，它会非常有效。

override func viewDidLoad() {
        super.viewDidLoad()
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
}

@objc func keyboardWillShow(notification: NSNotification) {
        if let _ = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
            self.view.frame.origin.y = self.navigationController!.navigationBar.frame.size.height + UIApplication.shared.statusBarFrame.size.height
            if self.emailTextField.isFirstResponder {
                self.view.frame.origin.y -= 100
            } else if self.passwordTextField.isFirstResponder {
                self.view.frame.origin.y -= 150
            } else if self.passwordConfirmTextField.isFirstResponder {
                self.view.frame.origin.y -= 200
            }
        }
}

@objc func keyboardWillHide(notification: NSNotification) {
        if self.view.frame.origin.y != 0 {
           self.view.frame.origin.y = self.navigationController!.navigationBar.frame.size.height + UIApplication.shared.statusBarFrame.size.height
        }
}

回答by Sreeraj VR

Try this

尝试这个

 override func viewDidLoad()
    {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow(notification:)), name: NSNotification.Name.UIKeyboardDidShow, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide(notification:)), name: NSNotification.Name.UIKeyboardDidHide, object: nil)
}

 @objc func keyboardWillShow(notification: NSNotification) {
      if(messageCount > 0)
      {
        tableView.scrollToRow(at: IndexPath(item:messageCount - 1, section: 0), at: .bottom, animated: true)
      }
}

@objc func keyboardWillHide(notification: NSNotification) {
    if(messageCount > 0)
    {
        tableView.scrollToRow(at: IndexPath(item:0, section: 0), at: .top, animated: true)
    }
}

回答by Giang

Swift 4.2

斯威夫特 4.2

NotificationCenter.default.addObserver(self, selector: #selector(didReceiveKeyboardNotificationObserver(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(didReceiveKeyboardNotificationObserver(_:)), name: UIResponder.keyboardWillHideNotification, object: nil)

@objc func didReceiveKeyboardNotificationObserver(_ notification: Notification) {
    let userInfo = notification.userInfo
    let keyboardBounds = (userInfo!["UIKeyboardBoundsUserInfoKey"] as! NSValue).cgRectValue
    let keyboardFrame = (userInfo!["UIKeyboardFrameEndUserInfoKey"] as! NSValue).cgRectValue
    let duration = userInfo!["UIKeyboardAnimationDurationUserInfoKey"] as! Double
    let curve = userInfo!["UIKeyboardAnimationCurveUserInfoKey"] as! Int
    let frameBegin = (userInfo!["UIKeyboardFrameBeginUserInfoKey"] as! NSValue).cgRectValue
    let centerBegin = (userInfo!["UIKeyboardCenterBeginUserInfoKey"] as! NSValue).cgPointValue
    let center = (userInfo!["UIKeyboardCenterEndUserInfoKey"] as! NSValue).cgPointValue
    let location = userInfo!["UIKeyboardIsLocalUserInfoKey"] as! Int
    println("keyboardBounds: \(keyboardBounds) \nkeyboardFrame: \(keyboardFrame) \nduration: \(duration) \ncurve: \(curve) \nframeBegin:\(frameBegin) \ncenterBegin:\(centerBegin)\ncenter:\(center)\nlocation:\(location)")
    switch notification.name {
    case UIResponder.keyboardWillShowNotification:
    // keyboardWillShowNotification
    case UIResponder.keyboardWillHideNotification:
    // keyboardWillHideNotification
    default:
        break
    }
}

回答by Kiran jadhav

Updated for swift:

快速更新：

// MARK:- Kyeboard hide/show methods

func keyboardWasShown(_ notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y == 0{
            self.view.frame.origin.y -= keyboardSize.height
        }
    }
}

func keyboardWillBeHidden(_ notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y != 0{
            self.view.frame.origin.y += keyboardSize.height
        }
    }
}

func registerForKeyboardNotifications(){
    //Adding notifies on keyboard appearing
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWasShown(_:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillBeHidden(_:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}

func deregisterFromKeyboardNotifications(){
    //Removing notifies on keyboard appearing
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillShow, object: nil)
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}

func textFieldDidBeginEditing(_ textField: UITextField) {
    if textField == mEnterPasswordTextField || textField == mEnterConfirmPassword  {
            animateViewMoving(up: true, moveValue: 120)
    }
}

func textFieldDidEndEditing(_ textField: UITextField) {
    if textField == mEnterPasswordTextField || textField == mEnterConfirmPassword  {
            animateViewMoving(up: false, moveValue: 120)
    }
}

func animateViewMoving (up:Bool, moveValue :CGFloat){
    let movementDuration:TimeInterval = 0.3
    let movement:CGFloat = ( up ? -moveValue : moveValue)
    UIView.beginAnimations( "animateView", context: nil)
    UIView.setAnimationBeginsFromCurrentState(true)
    UIView.setAnimationDuration(movementDuration )
    self.view.frame = self.view.frame.offsetBy(dx: 0,  dy: movement)
    UIView.commitAnimations()
}

// In viewDidLoad()

// 在 vi​​ewDidLoad()

self.registerForKeyboardNotifications()
self.deregisterFromKeyboardNotifications()

回答by Praveen Reddy

KeyBoard Will Show And Hide With TxtField In Swift 4

键盘将在 Swift 4 中使用 TxtField 显示和隐藏

class ViewController: UIViewController {


@IBOutlet weak var commentsTxt: UITextField!
@IBOutlet weak var keyboardBottom: NSLayoutConstraint!

override func viewWillAppear(_ animated: Bool) {
    IQKeyboardManager.shared.enable = false
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(keyboardWillShow),
        name: UIResponder.keyboardWillShowNotification,
        object: nil
    )
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(keyboarddidHide),
        name: UIResponder.keyboardWillHideNotification,
        object: nil
    )
}

@objc func keyboardWillShow(_ notification: Notification) {
    if let keyboardFrame: NSValue = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue {
        let keyboardRectangle = keyboardFrame.cgRectValue
        let keyboardHeight = keyboardRectangle.height
        self.keyboardBottom.constant = keyboardHeight - self.bottomLayoutGuide.length
        DispatchQueue.main.asyncAfter(deadline: .now()+0.1, execute: {
            let bottomOffset = CGPoint(x: 0, y: self.scrlView.contentSize.height - self.scrlView.bounds.size.height)
            self.scrlView.setContentOffset(bottomOffset, animated: true)
        })
    }
}
@objc func keyboarddidHide(_ notification: Notification) {
    self.keyboardBottom.constant = 0

}

   override func viewWillDisappear(_ animated: Bool) {
    IQKeyboardManager.shared.enable = true
     NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillHideNotification, object: nil)
}

}

}