Keyboard height change observer swift

Question

How to detect Keyboard height change, or keyboard change in iOS swift?
See my below code, it shows very small line in text keyboard and Emojis keyboard:

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardHideNShow(_:)), name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardHideNShow(_:)), name: UIKeyboardWillHideNotification, object: nil)
var didDisplayedKeyboard:Bool = false

func keyboardHideNShow(notification:NSNotification) {

var movement: CGFloat = 0.0
let userInfo:NSDictionary = notification.userInfo!
let keyboardFrame:NSValue = userInfo.valueForKey(UIKeyboardFrameEndUserInfoKey) as! NSValue
let keyboardRectangle = keyboardFrame.CGRectValue()

let movementDuration:NSTimeInterval = 0.3
UIView.beginAnimations( "animateView", context: nil)
UIView.setAnimationBeginsFromCurrentState(true)
UIView.setAnimationDuration(movementDuration )

if notification.name == UIKeyboardWillShowNotification {
    // Do the operation only if its hide n show or show n hide
    // When the keyboard switches from text to emoji, it wont hide the previous keyboard. will just replace
    //      In that case we need to avoid the keyboard movement
    if didDisplayedKeyboard == false {
        movement = -keyboardRectangle.height
        didDisplayedKeyboard = true
        print("m\(movement)")
        self.view.frame = CGRectOffset(self.view.frame, 0,  movement)
    }

} else if notification.name == UIKeyboardWillHideNotification {

    movement =  keyboardRectangle.height
    didDisplayedKeyboard = false
    self.view.frame = CGRectOffset(self.view.frame, 0,  movement)
}
UIView.commitAnimations()
}

How can I adjust my view?

Answer 1

Use UIKeyboardWillChangeFrameNotification notification like this:

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardWillChangeFrame(_:)), name: UIKeyboardWillChangeFrameNotification, object: nil)

And receive the changes as:

func keyboardWillChangeFrame(notification: NSNotification) {
    if let keyboardFrame = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue() {
        let keyboardHeight = keyboardFrame.size.height
        print("keyboard height: \(keyboardHeight)")
        //do the chnages according ot this height
    }
}

This notification will give us the keyboard frame rect when keyboard appears, changes to emoji, shows/hides predictions!

Answer 2

Swift 4:

 NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChangeFrame), name: UIResponder.keyboardWillChangeFrameNotification, object: nil)

Then, you can do something with the keyboard frame as such:

@objc func keyboardWillChangeFrame(_ notification: Notification) {
    if let keyboardFrame: NSValue = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue {
        let keyboardHeight = keyboardFrame.cgRectValue.size.height
        // Do something...
    }
}