Keyboard height needed before the textfield delegate is called - ios

Question

So I have the following code:
//MARK: - Textfield delegate Methods
func textFieldDidBeginEditing(textField: UITextField)
{
// update view based on updates in the constraints
self.view.layoutIfNeeded()
//perform animation to grow the dockview
UIView.animateWithDuration(0.5, animations: { () -> Void in
self.dockViewHeightConstraint.constant = self.keyBoardHeight + 60
self.view.layoutIfNeeded()
}, completion: nil)
}
and
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
}
func keyboardWillShow(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
let contentInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
keyBoardHeight = contentInsets.bottom
}
}
What I am trying to do is the following. When the user clicks on the textfield, the keyboard should open up, and the View which I made should move up.
I get the height from the keyboard from the keyboardWillShow function that is triggered by a NSNotification.
The problem is the following: when I run the code, the textFieldDidBeginEditing is being called before the NSNotification, making my self.keyBoardHeight value 0 (init value). Is there a way I can call the NSNotification part before pressing on the textField?

Answer 1

Set up a isKeyboardShown flag in your viewController to keep track whether keyboard is shown or not, the height which intersects with your element "myElement" can be captured in fieldMovement property as below
if !isKeyboardShown
{
if let info = notification.userInfo
{
if fieldMovement == nil
{
let window = UIApplication.sharedApplication().keyWindow
var keyboardEndRect = CGRectZero
//Get frame of keyboard view object
((info[UIKeyboardFrameEndUserInfoKey] as! NSValue)).getValue(&keyboardEndRect)
/* Convert the frame from the window's coordinate system to our view's coordinate system */
keyboardEndRect = view.convertRect(keyboardEndRect, fromView: window)
/* Find out how much of our view is being covered by the keyboard */
fieldMovement = CGRectIntersection(myElement.frame, keyboardEndRect).height
}
//Get animation duration of keyboard
var animationDuration: NSTimeInterval = 0
(info[UIKeyboardAnimationDurationUserInfoKey] as! NSValue).getValue(&animationDuration)
// Move views up by intersected height
UIView.animateWithDuration(animationDuration)
{
//animate your objects here
}
}
isKeyboardShown = true
}