Facebook Login - Facebook Authentication and Cocoapods

Create a new application facebook login and authentication a facebook user using their iOS SDK with Cocoapods. Below are the steps in which we'll be following: 

First Getting Started guide from Facebook's iOS SDK Documentation 

Create a new iOS project Swift

Open facebook Developer Account and create new App after go to setting and click basic -> add platform ios

https://developers.facebook.com/docs/ios/getting-started

https://developers.facebook.com/

Then add Bundle id your ios project like com.xxxx, Configuring Facebook with Bundle ID

Then go ahead Download facebook sdk for ios other wise install pod file your project.

Go ahead to open terminal and go ahead your project folder. 

Got create podfile -> pod init

Open podfile -> open podfile

Paste ->  pod 'FBSDKCoreKit' 
               pod 'FBSDKShareKit' 
               pod 'FBSDKLoginKit' podfile and save

Then go to terminal or install podfiles -> pod Install

Like 

Enabling Facebook's Authentication Mechanism

In order for your app to behave nicely with Facebook's authentication mechanism, you need to edit your .plist file according to the facebook authentication Step 4: Configure Xcode Project of the Getting Started guide. Go ahead and replace the placeholder strings with your Facebook App Id and Application name:

1. In Xcode, right-click your project's Info.plist file and select Open As -> Source Code. 
2. Insert the following XML snippet into the body of your file just before the final </dict> element.
3. Replace {your-app-id}, and {your-app-name} with your app's App's ID and name found on the Facebook App Dashboard.

Swift 3 AppDelegate Configurations 

Go to ahead swift project - AppDelegate.swift file. 

Import FBSDKCoreKit 

Next, FBSDKApplicationDelegate with in launchOptions 

like this afterwards:

import UIKit
import FBSDKCoreKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        
        FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)
        
        return true
    }
    
    func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {
        
        let handled = FBSDKApplicationDelegate.sharedInstance().application(app, open: url, sourceApplication: options[UIApplicationOpenURLOptionsKey.sourceApplication] as! String!, annotation: options[UIApplicationOpenURLOptionsKey.annotation])
        
        return handled
    }

    //...
}

Integration  FBSDKLoginButton

Open up ViewController.swift and make the following source code edit

import UIKit
import FSocialLogin

class ViewController: UIViewController, FBSDKLoginButtonDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let loginButton = FBSDKLoginButton()
        view.addSubview(loginButton)
        //frame's are obselete, please use constraints instead because its 2016 after all
        loginButton.frame = CGRect(x: 16, y: 50, width: view.frame.width - 32, height: 50)
        
        loginButton.delegate = self
    }
}

Output :-

After click loginButton

You will be able to grant permission for your iOS application to know about this user:

Keychain Sharing

In order to verify that the authentication is successful, you should implement the follow delegate methods and then set your button delegate:

ViewController.swift

class ViewController: UIViewController, FBSDKLoginButtonDelegate {

    override func viewDidLoad() {
        //...        
        loginButton.delegate = self
    }
    
    func loginButtonDidLogOut(_ loginButton: FBSDKLoginButton!) {
        print("Did log out of facebook")
    }
    
    func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {
        if error != nil {
            print(error)
            return
        }
        
        print("Successfully logged in with facebook...")
    }
}

If your Facebook doesn't show a "Log out" label, the authentication was mostly unsuccessful. To fix this, enable Keychain Sharing in your application settings in Xcode:

Run your application and perform the Log in authentication again. Now your button "Log out" label:

output: -

Facebook Login - Facebook Authentication and Cocoapods