swift-sample-firebase-auth-ViewController.swift

import UIKit
import Firebase
import FirebaseAuth

class ViewController: UIViewController {
    
    var microsoftProvider : OAuthProvider?
    let kGraphURI = "https://graph.microsoft.com/v1.0/me/"

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        self.microsoftProvider = OAuthProvider(providerID: "microsoft.com")
    }

    // the action when tap on Login by Office365 button
    @IBAction func tapLoginByOffice365(_ sender: Any) {

        self.microsoftProvider?.getCredentialWith(_: nil){credential, error in
            if error != nil {
                // Handle error.
            }
            if let credential = credential {
                Auth.auth().signIn(with: credential) { (authResult, error) in
                    if error != nil {
                        // Handle error.
                    }
                    
                    guard let authResult = authResult else {
                        print("Couldn't get graph authResult")
                        return
                    }
                    
                    // get credential and token when login successfully
                    let microCredential = authResult.credential as! OAuthCredential
                    let token = microCredential.accessToken!
                    
                    // use token to call Microsoft Graph API
                    self.getGraphContentWithToken(accessToken: token)
                }
            }
        }
    }

    // function to call Microsoft Graph API by token
    func getGraphContentWithToken(accessToken: String) {
        
        // Specify the Graph API endpoint
        let url = URL(string: kGraphURI)
        var request = URLRequest(url: url!)
        
        // Set the Authorization header for the request. We use Bearer tokens, so we specify Bearer + the token we got from the result
        request.setValue("Bearer \(accessToken)", forHTTPHeaderField: "Authorization")
        
        URLSession.shared.dataTask(with: request) { data, response, error in
            
            if let error = error {
                print("Couldn't get graph result: \(error)")
                return
            }
            
            guard let result = try? JSONSerialization.jsonObject(with: data!, options: []) else {
                
                print("Couldn't deserialize result JSON")
                return
            }
            
            print("Result from Graph: \(result))")
            
            }.resume()
    }
}