how to use observer selector function in different ViewControllers - ios

Question

I have login and registration forms in my application. When user tap any textField I calculate the difference in height of keyboard and textField and scroll my view if needed.
For this I've added two observers in loginVC:
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)
func keyboardWillShow(notification: NSNotification) {
println("keyb show")
keyboardIsShown = true
keyboardHeight = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue().height
calculateAnimationValue()
}
func keyboardWillHide(notification: NSNotification) {
println("keyb hide")
keyboardIsShown = false
animateViewMoving(false, moveValue: animationValue)
animationValue = 0
}
func textFieldDidBeginEditing(textField: UITextField) {
pressedTextField = textField
textField.becomeFirstResponder()
if keyboardIsShown {
calculateAnimationValue()
}
}
func calculateAnimationValue() {
if keyboardHeight != nil {
var windowHeight = self.view.frame.height
var textFieldY = pressedTextField.frame.origin.y
var windowWithoutKeyboard = windowHeight - keyboardHeight - 44
if textFieldY > windowWithoutKeyboard {
if animationValue < (textFieldY - windowWithoutKeyboard) {
animationValue = animationValue + textFieldY - windowWithoutKeyboard
animateViewMoving(true, moveValue: animationValue)
}
}
}
println(animationValue)
}
func animateViewMoving (up: Bool, moveValue: CGFloat){
var movementDuration: NSTimeInterval = 0.3
var movement:CGFloat = (up ? -moveValue : moveValue)
UIView.beginAnimations("animateView", context: nil)
UIView.setAnimationBeginsFromCurrentState(true)
UIView.setAnimationDuration(movementDuration)
self.view.frame = CGRectOffset(self.view.frame, 0, movement)
UIView.commitAnimations()
}
But I want to do the same in registrationVC.
How can I use keyboardWillShow, keyboardWillHide in another VC?
I've tried to add the same observers but then the application fires these methods in loginVC not in registrationVC.
Can someone help me?
UPDATE: ------------------------
class LogInViewController: UIViewController, UITextFieldDelegate {
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)
}
func keyboardWillShow(notification: NSNotification) {
println("keyb show")
}
func keyboardWillHide(notification: NSNotification) {
println("keyb hide")
}
}
class RegistrationViewController: UIViewController, UITextFieldDelegate {
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)
}
func keyboardWillShow(notification: NSNotification) {
println("keyb show2")
}
func keyboardWillHide(notification: NSNotification) {
println("keyb hide2")
}
deinit {
println("deinit")
NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
}
}
If I touch textField's on loginVC and segue to registerVC it works well and prints "keyb show2".
But if didn't touch textField's on loginVC and segue to registerVC and touch textField it prints "keyb show". Which is called from previous controller. What I am doing wrong?