SwiftUITrackKeyboardInteractiveDismissal.swift

import SwiftUI
import UIKit

struct ContentView: View {
	@State private var offset: CGFloat = 0
	@State private var keyboardOpened: Bool = false
	
	var body: some View {
		VStack(spacing: 0) {
			ScrollView {
				ForEach(0..<20) { index in
					HStack {
						Text("Item \(index + 1)")
							.padding()
						Spacer()
					}
				}
			}
			.scrollDismissesKeyboard(.interactively)
			.scrollClipDisabled()
			.defaultScrollAnchor(.bottom)
			.padding(.bottom, -offset)
			TextInputView()
				.offset(y: offset)
		}
		.background {
			KeyboardAttachedView(
				offset: $offset,
				onKeyboardDidShow: {
					keyboardOpened = true
				},
				onKeyboardDidHide: {
					keyboardOpened = false
				}
			)
			.frame(height: 0)
			.frame(maxHeight: .infinity, alignment: .bottom)
		}
		.animation(.spring(duration: 0.3), value: keyboardOpened ? nil : offset)
		.ignoresSafeArea(.keyboard)
	}
}

struct TextInputView: View {
	@State private var textFieldText = ""
	var body: some View {
		TextField("Type here", text: $textFieldText)
			.textFieldStyle(RoundedBorderTextFieldStyle())
			.padding()
	}
}

struct KeyboardAttachedView: UIViewControllerRepresentable {
	var offset: Binding<CGFloat>
	var onKeyboardDidShow: (() -> Void)?
	var onKeyboardDidHide: (() -> Void)?
	
	func makeUIViewController(context: Context) -> KeyboardObservingViewController {
		let viewController = KeyboardObservingViewController(offset: offset)
		viewController.onKeyboardDidShow = onKeyboardDidShow
		viewController.onKeyboardDidHide = onKeyboardDidHide
		return viewController
	}
	func updateUIViewController(_ uiViewController: KeyboardObservingViewController, context: Context) {}
}

class KeyboardObservingViewController: UIViewController {
	var offset: Binding<CGFloat>
	var onKeyboardDidShow: (() -> Void)?
	var onKeyboardDidHide: (() -> Void)?
	var emptyView: UIView = UIView()

	init(offset: Binding<CGFloat>) {
		self.offset = offset
		super.init(nibName: nil, bundle: nil)
		setupKeyboardNotifications()
	}

	required init?(coder: NSCoder) {
		fatalError("init(coder:) has not been implemented")
	}
	
	override func viewDidAppear(_ animated: Bool) {
		super.viewDidAppear(animated)
		view.addSubview(emptyView)
		emptyView.translatesAutoresizingMaskIntoConstraints = false
		emptyView.bottomAnchor.constraint(equalTo: view.keyboardLayoutGuide.topAnchor).isActive = true
		emptyView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
		emptyView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
	}

	override func viewDidLayoutSubviews() {
		super.viewDidLayoutSubviews()
		offset.wrappedValue = emptyView.layer.position.y
	}
	
	private func setupKeyboardNotifications() {
		NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidShow), name: UIResponder.keyboardDidShowNotification, object: nil)
		NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidHide), name: UIResponder.keyboardDidHideNotification, object: nil)
	}
	
	@objc private func keyboardDidShow(notification: Notification) {
		onKeyboardDidShow?()
	}
	
	@objc private func keyboardDidHide(notification: Notification) {
		onKeyboardDidHide?()
	}
	
	deinit {
		NotificationCenter.default.removeObserver(self)
	}
}