Firebase authentication intial view setup.

ContentView.swift

// Main App File.
import SwiftUI
import Firebase

@main
struct MediumArticleApp: App {
    @StateObject var authViewModel = AuthViewModel()
    init() {
        FirebaseApp.app()
    }
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(authViewModel)
        }
    }
}
// Content View file.
import SwiftUI

struct ContentView: View {
    @State private var email = ""
    @State private var password = ""
    @State private var fullname = ""
    @State private var username = ""
    @EnvironmentObject var authViewModel: AuthViewModel
    
    var body: some View {
        VStack {
            TextField("Full Name", text: $fullname)
            TextField("Username", text: $username)
            TextField("Email", text: $email)
            SecureField("Password", text: $password)
            Button {
                authViewModel.registerUser(withEmail: email, password: password, fullname: fullname, username: username)
            } label: {
                Text("Submit Registration")
            }
            .padding(.top)

        }
        .textFieldStyle(RoundedBorderTextFieldStyle())
        .padding(.horizontal)
    }
}