1. Views of the Screens

Views

The design of the screens is the same except for the background color of the color box. So, let's create the views of Red, Blue, and Green screens.

RedView.swift

Let's create a swift file called RedView.swift and put the following code:

//
//  RedView.swift
//  TabControllerDemo
//
//  Created by Sakib Miazi on 6/6/23.
//

import UIKit

class RedView: UIView {
    var boxView: UIView!
    var buttonSend: UIButton!
    var labelReceived: UILabel!
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        boxView = UIView()
        boxView.backgroundColor = .red
        boxView.translatesAutoresizingMaskIntoConstraints = false
        self.addSubview(boxView)
        
        buttonSend = UIButton(type: .system)
        buttonSend.setTitle("Send Hello", for: .normal)
        buttonSend.translatesAutoresizingMaskIntoConstraints = false
        self.addSubview(buttonSend)
        
        labelReceived = UILabel()
        labelReceived.text = "Waiting for Notification!"
        labelReceived.translatesAutoresizingMaskIntoConstraints = false
        self.addSubview(labelReceived)
        
        
        NSLayoutConstraint.activate([
            boxView.topAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 32),
            boxView.widthAnchor.constraint(equalToConstant: 200),
            boxView.heightAnchor.constraint(equalToConstant: 200),
            boxView.centerXAnchor.constraint(equalTo: self.safeAreaLayoutGuide.centerXAnchor),
            
            buttonSend.topAnchor.constraint(equalTo: self.boxView.bottomAnchor, constant: 8),
            buttonSend.centerXAnchor.constraint(equalTo: self.safeAreaLayoutGuide.centerXAnchor),
            
            labelReceived.topAnchor.constraint(equalTo: self.buttonSend.bottomAnchor, constant: 8),
            labelReceived.centerXAnchor.constraint(equalTo: self.safeAreaLayoutGuide.centerXAnchor),
        ])
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

In the above code, we create a boxView to display the corresponding color of the screen, a button to send data to other screens, and a label to display the received data.

GreenView.swift and BlueView.swift

The only thing different in these files compared to RedView.swift is the background color of the boxView. For GreenView.swift, it is .green, and for BlueView.swift, it is .blue.