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“If you’re in a situation where your iOS app has multiple UITextField instances lined up, users expect to be able to move between them by pressing Next/Return on their on-screen keyboard. There is no built-in way of making this happen, so we need to write code ourselves using one of several approaches.

The easiest approach is using view tags: give your text fields incrementing tag numbers, then make them all point to a common delegate – it might be your view controller, but it doesn’t need to be.

Once that’s done you can use the becomeFirstResponder() and resignFirstResponder() methods to manipulate which view is in control like this:

func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    let nextTag = textField.tag + 1

    if let nextResponder = textField.superview?.viewWithTag(nextTag) {
        nextResponder.becomeFirstResponder()
    } else {
        textField.resignFirstResponder()
    }

    return true
}”

“Note: If you ever need to force the first responder to resign itself and aren’t sure which text field is in control, it’s easier to use view.endEditing(true).

The other task you might want to do is find the view controller that is responsible for a particular view, usually to communicate something important. This is as easy as walking the responder chain looking for the first UIViewController you find, like this:

func findViewController() -> UIViewController? {
    if let nextResponder = self.next as? UIViewController {
        return nextResponder
    } else if let nextResponder = self.next as? UIView {
        return nextResponder.findViewController()
    } else {
        return nil”

Excerpt From: Paul Hudson. “Swift Design Patterns.” Apple Books.