KeyboardToolbarDemo.swift

//
//  keyboardToolBar.swift
//  ios14-demo
//
//  Created by Prafulla Singh on 4/10/20.
//

import SwiftUI

final class KeyboardResponder: ObservableObject {
    
    private var notificationCenter: NotificationCenter
    @Published private(set) var currentHeight: CGFloat = 0

    init(center: NotificationCenter = .default) {
        notificationCenter = center
        notificationCenter.addObserver(self, selector: #selector(keyBoardWillShow(notification:)), name: UIResponder.keyboardWillShowNotification, object: nil)
        notificationCenter.addObserver(self, selector: #selector(keyBoardWillHide(notification:)), name: UIResponder.keyboardWillHideNotification, object: nil)
    }

    func dismiss() {
        UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
    }
    
    deinit {
        notificationCenter.removeObserver(self)
    }

    @objc func keyBoardWillShow(notification: Notification) {
        if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
            currentHeight = keyboardSize.height
        }
    }

    @objc func keyBoardWillHide(notification: Notification) {
        currentHeight = 0
    }
}

struct KeyboardView<Content, ToolBar> : View where Content : View, ToolBar: View {
    @StateObject private var keyboard: KeyboardResponder = KeyboardResponder()
    let toolbarFrame: CGSize = CGSize(width: UIScreen.main.bounds.width, height: 40.0)
    var content: () -> Content
    var toolBar: () -> ToolBar
    
    var body: some View {
        ZStack {
            content()
                .padding(.bottom, (keyboard.currentHeight == 0) ? 0 : toolbarFrame.height)
            VStack {
                 Spacer()
                 toolBar()
                    .frame(width: toolbarFrame.width, height: toolbarFrame.height)
                    .background(Color.secondary)
            }.opacity((keyboard.currentHeight == 0) ? 0 : 1)
            .animation(.easeOut)
        }
        .padding(.bottom, keyboard.currentHeight)
        .edgesIgnoringSafeArea(.bottom)
        .animation(.easeOut)
        
    }
}

struct KeyboardToolBar: View {
    @State private var name: String = ""
    @State private var phoneNumber: String = ""
    var body: some View {
        
        NavigationView {
            KeyboardView {
                ScrollView {
                    Spacer()
                    Text("Welcome")
                        .font(.largeTitle)
                    VStack {
                        TextField("Name", text: $name)
                            .padding()
                            .overlay(RoundedRectangle(cornerRadius: 8)
                            .stroke(Color.secondary, lineWidth: 1)
                            .frame(height: 50))
                            .keyboardType(.namePhonePad)
                        
                        TextField("Phone Number", text: $phoneNumber)
                            .padding()
                            .overlay(RoundedRectangle(cornerRadius: 8)
                            .stroke(Color.secondary, lineWidth: 1)
                            .frame(height: 50))
                            .keyboardType(.numberPad)
                        
                        Button(action: {
                            
                        }, label: {
                            Text("Continue")
                        })
                        .padding()
                        .overlay(RoundedRectangle(cornerRadius: 8)
                        .stroke(Color.secondary, lineWidth: 1))
                        
                        
                            
                    }.padding()
                }
            } toolBar: {
                HStack {
                    Spacer()
                    Button(action: {
                        UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
                    }, label: {
                        Text("Done")
                    })
                }.padding()
            }
            .navigationBarTitle("Sign Up", displayMode: .inline)
        }
    }
}

struct keyboardToolBar_Previews: PreviewProvider {
    static var previews: some View {
        KeyboardToolBar()
    }
}