Text Field- Show what is inside the text field right above the keyboard

I’ve struggled with this for, oh, about a decade )-: Eventually I moved the core code out into a separate helper type (pasted in below). If my content is in a scroll view, I set it up and respond as follows:

var avoider: KeyboardAvoider? = nil

override func viewDidLoad() {
    …

    let avoider = KeyboardAvoider(view: self.mainText)
    avoider.delegate = self
    self.avoider = avoider

    …
}

func inset(by inset: CGFloat, keyboardAvoider: KeyboardAvoider) {
    let insets = UIEdgeInsets(top: 0.0, left: 0.0, bottom: inset, right: 0.0)
    self.mainText.contentInset = insets 
    self.mainText.scrollIndicatorInsets = insets
    // UITextView seems to take care of the 'scoll active text to be visible' problem.
}

If my content is just a bunch of separate views I put an invisible wrapper view around them and then set up a constraint in order to inset that wrapper view. My delegate callback adjusts the constant on that constraint, like this:

func inset(by inset: CGFloat, keyboardAvoider: KeyboardAvoider) {
    self.bottomConstraint.constant = inset 
}

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

import UIKit

class KeyboardAvoider : NSObject {

    typealias Delegate = KeyboardAvoiderDelegate

    private override init() {
        fatalError()
    }

    required init(view: UIView) {
        self.view = view
        super.init()
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidShow(note:)), name: .UIKeyboardDidShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(note:)), name: .UIKeyboardWillHide, object: nil)
    }

    let view: UIView

    weak var delegate: Delegate? = nil

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    private static let logTransitions = false

    @objc func keyboardDidShow(note: Notification) {
        let new = (note.userInfo![UIKeyboardFrameEndUserInfoKey]! as! NSValue).cgRectValue
        let newInViewCoordinates = self.view.superview!.convert(new, from: UIScreen.main.coordinateSpace)
        let keyboardTop = newInViewCoordinates.minY
        let viewBottom = self.view.frame.maxY

        let inset: CGFloat
        if keyboardTop < viewBottom {
            inset = viewBottom - keyboardTop
        } else {
            inset = 0.0
        }
        if (KeyboardAvoider.logTransitions) {
            NSLog("did show, view.bottom: %.1f, keyboard.top: %.1f, inset: %.1f", viewBottom, keyboardTop, inset)
        }
        self.delegate?.inset(by: inset, keyboardAvoider: self)
    }

    @objc func keyboardWillHide(note: Notification) {
        if (KeyboardAvoider.logTransitions) {
            NSLog("did hide, inset: 0.0")
        }
        self.delegate?.inset(by: 0.0, keyboardAvoider: self)
    }
}

protocol KeyboardAvoiderDelegate : AnyObject {
    func inset(by inset: CGFloat, keyboardAvoider: KeyboardAvoider)
}