UITextField is partially hidden by Keyboard when opened - swift

Question

I am attempting to create a collection of UITextField elements. I'd like the next button on the keyboard to skip to the next field and if that field is hidden from view by the keyboard, scroll it into view.
This is my attempt. It works apart from 1 aspect.
When dismissing the keyboard and then selecting another (or the same) field, the text input is partially hidden by the keyboard (see attached gif).
The meat and potatoes is within the ViewController extension.
class ViewController: UIViewController {
var activeField: UITextField?
var lastOffset: CGPoint!
var keyboardHeight: CGFloat!
let scrollView: UIScrollView = {
let scrollView = UIScrollView()
scrollView.translatesAutoresizingMaskIntoConstraints = false
return scrollView
}()
let scrollViewContainer: UIStackView = {
let view = UIStackView()
view.axis = .vertical
view.spacing = 10
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
view.addSubview(scrollView)
scrollView.addSubview(scrollViewContainer)
let totalFieldCount = 25
for i in 1...totalFieldCount {
let textField = createTextField(self, placeholder: "Field #\(i)", type: .default)
textField.returnKeyType = i < totalFieldCount ? .next : .done
textField.tag = i
scrollViewContainer.addArrangedSubview(textField)
}
NSLayoutConstraint.activate([
scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
scrollView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
scrollViewContainer.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
scrollViewContainer.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
scrollViewContainer.topAnchor.constraint(equalTo: scrollView.topAnchor),
scrollViewContainer.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
scrollViewContainer.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
])
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
scrollView.keyboardDismissMode = .interactive
}
func createTextField(_ delegate: UITextFieldDelegate?, placeholder: String, type: UIKeyboardType, isSecureEntry: Bool = false) -> UITextField {
let tf = UITextField(frame: .zero)
tf.placeholder = placeholder
tf.backgroundColor = .init(white: 0, alpha: 0.03)
tf.borderStyle = .roundedRect
tf.font = .systemFont(ofSize: 14)
tf.keyboardType = type
tf.autocapitalizationType = .none
tf.autocorrectionType = .no
tf.isSecureTextEntry = isSecureEntry
tf.heightAnchor.constraint(equalToConstant: 40).isActive = true
if let delegate = delegate {
tf.delegate = delegate
}
return tf
}
}
extension ViewController: UITextFieldDelegate {
func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
activeField = textField
lastOffset = self.scrollView.contentOffset
return true
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
let nextTag = textField.tag + 1
if let nextResponder = textField.superview?.viewWithTag(nextTag) {
nextResponder.becomeFirstResponder()
} else {
activeField?.resignFirstResponder()
activeField = nil
}
return true
}
}
extension ViewController {
#objc func keyboardWillShow(notification: NSNotification) {
guard keyboardHeight == nil else { return }
if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
keyboardHeight = keyboardSize.height
UIView.animate(withDuration: 0.3, animations: {
self.scrollView.contentInset.bottom = self.keyboardHeight
})
guard let activeField = activeField else { return }
let distanceToBottom = self.scrollView.frame.size.height - (activeField.frame.origin.y) - (activeField.frame.size.height)
let collapseSpace = keyboardHeight - distanceToBottom
guard collapseSpace > 0 else { return }
UIView.animate(withDuration: 0.3, animations: {
self.scrollView.contentOffset = CGPoint(x: self.lastOffset.x, y: collapseSpace + 10)
})
}
}
#objc func keyboardWillHide(notification: NSNotification) {
UIView.animate(withDuration: 0.3) {
self.scrollView.contentOffset = self.lastOffset
self.scrollView.contentInset.bottom = 0
}
keyboardHeight = nil
}
}

Answer 1

Replace keyboardFrameBeginUserInfoKey with keyboardFrameEndUserInfoKey