sdk-for-apple/example-swiftui/iOS/Keyboard.swift

//
// Created by Jake Barnby on 4/08/21.
//

import SwiftUI
import Combine

final class Keyboard: ObservableObject {

    @Published var height: CGFloat = 0

    var cancellables: Set<AnyCancellable> = []

    init() {
        NotificationCenter.default.publisher(for: UIResponder.keyboardWillChangeFrameNotification)
            .compactMap({ (notification) -> CGFloat? in
                guard let frame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect else {
                    return nil
                }
                if frame.origin.y == UIScreen.main.bounds.height {
                    return 0
                }
                return frame.size.height
            })
            .assign(to: \.height, on: self)
            .store(in: &cancellables)
    }

    deinit {
        cancellables.forEach {
            $0.cancel()
        }
    }
}