[FIXED] How to login to Facebook on SwiftUI?

Issue

There are not many resources explaining Facebook Login with SwiftUI. I'm not sure whether my code requires a ViewController or not because Facebook's LoginManager.login() contains a ViewController parameter - however this doesn't really translate to SwiftUI.

Regardless, I am trying to login the user to Facebook when they click on the Button below:

LoginView.swift

import Foundation
import SwiftUI
import FBSDKLoginKit

struct LoginView: View {
    @EnvironmentObject var auth: UserAuth
    var body: some View {
        ZStack {
            VStack {
                Image("launcher_logo").resizable()
                .scaledToFit()
                .frame(height: 100)
                    .padding(.top, 100)
                Spacer()
                Button(action: {
                    FBLogin()
                }) {
                    Text("Continue with Facebook")
                }.foregroundColor(Color.black)

when the Button is clicked, it initialises FBLogin below - which fires login() in its init():

Model:

class FBLogin: LoginManager {

    let loginButton = FBLoginButton()
    let token = AccessToken.current
    let permissions = ["user_birthday", "user_gender", "public_profile"]

    override init(){
        super.init()
        logIn(permissions: permissions, from: nil)
        print("fb init()")
    }

    override func logIn(permissions: [String], from fromViewController: UIViewController?, handler: LoginManagerLoginResultBlock? = nil) {
        // TODO
    }

}

However I'm not sure what to do from there. At the moment, only fb init() prints but I want to execute the login and listen to the login result.

Any idea?

Solution

Just create LoginManager instance inside ObservableObject and then customise login completion. You can easily use inside SwiftUI View. No need UIViewControllerRepresentable. Here is my sample.

struct ContentView: View {
    @ObservedObject var fbmanager = UserLoginManager()
    var body: some View {
        Button(action: {
            self.fbmanager.facebookLogin()
        }) {
            Text("Continue with Facebook")
        }
    }
}

class UserLoginManager: ObservableObject {
    let loginManager = LoginManager()
    func facebookLogin() {
        loginManager.logIn(permissions: [.publicProfile, .email], viewController: nil) { loginResult in
            switch loginResult {
            case .failed(let error):
                print(error)
            case .cancelled:
                print("User cancelled login.")
            case .success(let grantedPermissions, let declinedPermissions, let accessToken):
                print("Logged in! \(grantedPermissions) \(declinedPermissions) \(accessToken)")
                GraphRequest(graphPath: "me", parameters: ["fields": "id, name, first_name"]).start(completionHandler: { (connection, result, error) -> Void in
                    if (error == nil){
                        let fbDetails = result as! NSDictionary
                        print(fbDetails)
                    }
                })
            }
        }
    }
}

Answered By - Scotti

Answer Checked By - Terry (PHPFixing Volunteer)