CustomInputView.swift

import UIKit

class ViewController: UIViewController {
    private var customInput = false
    private let textInput = UITextField()
    private var leadingBarButtonGroups: [UIBarButtonItemGroup] = []
    private var trailingBarButtonGroups: [UIBarButtonItemGroup] = []

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillChangeFrameNotification, object: nil, queue: nil) { notification in
            print(notification.userInfo!)
        }

        view.backgroundColor = .systemBackground

        textInput.borderStyle = .roundedRect
        textInput.backgroundColor = .secondarySystemBackground
        view.addSubview(textInput)
        textInput.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            textInput.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            textInput.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            textInput.widthAnchor.constraint(equalToConstant: 200)
        ])

        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(toggleInputView))
        view.addGestureRecognizer(tapGesture)

        let longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(dismissKeyboard))
        view.addGestureRecognizer(longPressGesture)
    }

    @objc private func dismissKeyboard() {
        view.endEditing(true)
    }

    @objc private func toggleInputView() {
        guard textInput.isFirstResponder else { return }

        customInput.toggle()

        if customInput {
            let inputView = UIView(frame: CGRect(origin: .zero, size: CGSize(width: 0, height: 300)))
            inputView.backgroundColor = .systemRed
            textInput.inputView = inputView

            let inputAccessoryView = UIView(frame: CGRect(origin: .zero, size: CGSize(width: 0, height: 44)))
            inputAccessoryView.backgroundColor = .systemOrange
            textInput.inputAccessoryView = inputAccessoryView

            leadingBarButtonGroups = textInput.inputAssistantItem.leadingBarButtonGroups
            trailingBarButtonGroups = textInput.inputAssistantItem.trailingBarButtonGroups
            textInput.inputAssistantItem.leadingBarButtonGroups = []
            textInput.inputAssistantItem.trailingBarButtonGroups = []
        } else {
            textInput.inputView = nil
            textInput.inputAccessoryView = nil
            textInput.inputAssistantItem.leadingBarButtonGroups = leadingBarButtonGroups
            textInput.inputAssistantItem.trailingBarButtonGroups = trailingBarButtonGroups
        }

        textInput.reloadInputViews()
    }
}