How to detect when keyboard is shown and hidden

In the ViewDidLoad method of your class set up to listen for messages about the keyboard:

// Listen for keyboard appearances and disappearances[[NSNotificationCenter defaultCenter] addObserver:self                                          selector:@selector(keyboardDidShow:)                                             name:UIKeyboardDidShowNotification                                           object:nil];[[NSNotificationCenter defaultCenter] addObserver:self                                         selector:@selector(keyboardDidHide:)                                             name:UIKeyboardDidHideNotification                                           object:nil];

Then in the methods you specify (in this case keyboardDidShow and keyboardDidHide) you can do something about it:

- (void)keyboardDidShow: (NSNotification *) notif{    // Do something here}- (void)keyboardDidHide: (NSNotification *) notif{    // Do something here}

You may just need addObserver in viewDidLoad. But having addObserver in viewWillAppear and removeObserver in viewWillDisappear prevents rare crashes which happens when you are changing your view.

Swift 4.2

override func viewWillAppear(_ animated: Bool) {    super.viewWillAppear(animated)    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillDisappear), name: UIResponder.keyboardWillHideNotification, object: nil)    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillAppear), name: UIResponder.keyboardWillShowNotification, object: nil)}@objc func keyboardWillAppear() {    //Do something here}@objc func keyboardWillDisappear() {    //Do something here}override func viewWillDisappear(_ animated: Bool) {    super.viewWillDisappear(animated)    NotificationCenter.default.removeObserver(self)}

Swift 3 and 4

override func viewWillAppear(_ animated: Bool) {    super.viewWillAppear(animated)    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillDisappear), name: Notification.Name.UIKeyboardWillHide, object: nil)    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillAppear), name: Notification.Name.UIKeyboardWillShow, object: nil)}@objc func keyboardWillAppear() {    //Do something here}@objc func keyboardWillDisappear() {    //Do something here}override func viewWillDisappear(_ animated: Bool) {    super.viewWillDisappear(animated)    NotificationCenter.default.removeObserver(self)}

Older Swift

override func viewWillAppear(animated: Bool) {    super.viewWillAppear(animated)    NSNotificationCenter.defaultCenter().addObserver(self, selector:"keyboardWillAppear:", name: UIKeyboardWillShowNotification, object: nil)    NSNotificationCenter.defaultCenter().addObserver(self, selector:"keyboardWillDisappear:", name: UIKeyboardWillHideNotification, object: nil)}func keyboardWillAppear(notification: NSNotification){    // Do something here}func keyboardWillDisappear(notification: NSNotification){    // Do something here}override func viewWillDisappear(animated: Bool) {    super.viewWillDisappear(animated)    NSNotificationCenter.defaultCenter().removeObserver(self)}

Swift 3:

NotificationCenter.default.addObserver(self, selector: #selector(viewController.keyboardWillShow(_:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)NotificationCenter.default.addObserver(self, selector: #selector(viewController.keyboardWillHide(_:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)func keyboardWillShow(_ notification: NSNotification){    // Do something here}func keyboardWillHide(_ notification: NSNotification){    // Do something here}