How to login to Facebook on SwiftUI? - ios

Question

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?

Answer 1

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)
}
})
}
}
}
}

Answer 2

Have a look on a callback wrapper for Combine to use Facebook Login and Graph API Request with SwiftUI: https://github.com/axmav/combine-extensions
LoginManager()
.logIn(permissions: [.publicProfile, .email])
.flatMap { loginResult -> AnyPublisher<Account?, Error> in
switch loginResult {
case .failed(let error):
return Fail(outputType: Account?.self, failure: error).eraseToAnyPublisher()
case .cancelled:
return Just(Account?.none)
.setFailureType(to: Error.self)
.eraseToAnyPublisher()
case .success(let grantedPermissions, let declinedPermissions, let accessToken):
return GraphRequest(graphPath: "me", parameters: ["fields": "id, name, first_name"])
.start(type: Account.self)
}
}