Move view up only if certain textField is selected - ios

Question

I am trying to move my view up only if certain textField is selected. I got it working, however, if I now select other textField, it activates again on other textFields also, why?
Like this I am dealing with the moving:
func keyboardWillShow(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
if self.view.frame.origin.y == 0{
self.view.frame.origin.y -= keyboardSize.height
}
}
}
func keyboardWillHide(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
if self.view.frame.origin.y != 0{
self.view.frame.origin.y += keyboardSize.height
}
}
}
And like this I am trying to addObserver in textField touchDown:
#IBAction func didTapCertainTextField(_ sender: Any) {
NotificationCenter.default.addObserver(self, selector: #selector(CreateCardViewController.keyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
}
Flow in words:
Lets say I have 5 textFields(1, 2, 3, 4, 5)
I add the observer to third textField. I click first, view doesn't move, I click third it moves, I click 1 again and now it moves. Why? I do not want the view to move if clicked textField is 1.

Answer 1

What you are looking for is to know if the textField is first responder, but what you are doing is getting notified when the keyboard is displayed.
I encourage you to look into this class of cocoa:
https://developer.apple.com/reference/uikit/uiresponder
Or you can in the precise cas of you UITextField bind actions to EditingDidBegin and EditingDidEnd through you the Xcode interface builder
or do it programmatically with a delegate
https://developer.apple.com/reference/uikit/uitextfielddelegate
Also I can notice that you start observing this events but it seems to me that you never stop observing them.
For that you should call removeObserver:name:object: at some point before the end of your object's life time

Answer 2

If I understand you correctly, you're trying to move the view up only when the keyboard is hiding the UITextField. If that is the case, I wrote the following extension specifically for that:
extension UIViewController {
func pushViewForTextFields() {
// Push view according text field's position
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow), name:NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide), name:NSNotification.Name.UIKeyboardWillHide, object: nil)
}
#objc func keyboardWillShow(_ sender: Notification) {
var currentEditingTextField: UITextField!
let keyboardHeight = UIScreen.main.bounds.maxY - ((sender as NSNotification).userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue.height
// Find which text field is currently editing (O(n))
for view in self.view.subviews as [UIView] {
if let tf = view as? UITextField {
if tf.isEditing {
currentEditingTextField = tf
break
}
}
}
if currentEditingTextField == nil || currentEditingTextField < 0 {
// no textfield found
return
}
// get absolute frame of the text field, regardless of its parent view
let globalFrame = (currentEditingTextField.superview?.convert(senderObject.frame, to: self.view))!
// the 30 below is completely arbitrary; change it to whatever you want to suit your needs. This is basically the distance you want between the top of the keyboard and the editing text field (30px)
if globalFrame.maxY + 30 > keyboardHeight {
self.view.frame.origin.y = -(globalFrame.maxY + 30 - keyboardHeight)
}
else { // keyboard not covering the text field
self.view.frame.origin.y = 0
}
}
#objc func keyboardWillHide(_ sender: Notification) {
// move view back to normal position when editing is done
self.view.frame.origin.y = 0
}
}
Then simply use it in your UIViewController like this
override func viewDidLoad() {
super.viewDidLoad()
self.pushViewForTextFields()
}
Note that this extension only works if your UITextField objects are on the top level of the main UIView. i.e if they're not embedded in any subViews. If you have any text field in a subview, then you'll have to expand the for-loop by nesting another for-loop in there to check for every view in every subview (O(n^2) in this case).
This may not be the most efficient way (with looping over the UIView's tree and all), but I only wrote it to have a generic solution that I can easily apply to all my UIViewControllers