How to switch custom in-app keyboards - ios

Question

Recently I learned to make custom in-app keyboards. Now I want to be able to swap between multiple custom keyboards. However, resetting the textField.inputView property does not seem to work.
I recreated a simplified version of this problem in the following project. The UIViews represent actual custom keyboards.
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
let blueInputView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: 300))
blueInputView.backgroundColor = UIColor.blueColor()
textField.inputView = blueInputView
textField.becomeFirstResponder()
}
#IBAction func changeInputViewButtonTapped(sender: UIButton) {
let yellowInputView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: 300))
yellowInputView.backgroundColor = UIColor.yellowColor()
// this doesn't cause the view to switch
textField.inputView = yellowInputView
}
}
Running this gives what I would initially expect: a blue input view pops up.
But when I tap the button to switch to the yellow input view, nothing happens. Why? What do I need to do to get this to work?

Answer 1

After a little more experimenting I have the solution now. I needed to resign the first responder and then set it again. Any first responder that is a subview of the top view can be resigned indirectly by calling endEditing.
#IBAction func changeInputViewButtonTapped(sender: UIButton) {
let yellowInputView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: 300))
yellowInputView.backgroundColor = UIColor.yellowColor()
// first do this
self.view.endEditing(true)
// or this
//textField.resignFirstResponder()
textField.inputView = yellowInputView
textField.becomeFirstResponder()
}
Thanks to this and this answer for the ideas.