Facebook SDK and Swift - Create a Facebook Login Button

Update (November 7, 2016) - Swift 3.0.1 (Xcode 8.1)
This tutorial shows how to create a Facebook login button using Swift 2.1.1 (Xcode 7.2).

Objective-C programmers may directly refer to the instructions in Quick Start for iOS (Login with your Facebook account and select iOS.)

Steps to create a Facebook login button

1. Download Facebook SDK for iOS and unzip it to your preferred directory.

2. Create a new Facebook App online.

Login with your Facebook account and select iOS.

Enter the App Name and select Create New Facebook App ID. 

3. Create an iOS Single View Application with Xcode.

4. Drag these framework files into the Xcode project.
FBSDKCoreKit.Framework
FBSDKLoginKit.Framework
FBSDKShareKit.Framework

Bolts.framework //Update Nov. 7, 2016 with Xcode 8.1
//See Why am I getting an error regarding Bolts framework and FacebookSDK when I'm not even using Bolts?

5. Right-click on Info.plist and select Open As -> Source Code.

6. Copy and paste XML snippets from Configure your info.plist section of the Quick Start for iOS webpage the into Info.plist.

<key>CFBundleURLTypes</key>
<array>
  <dict>
  <key>CFBundleURLSchemes</key>
  <array>
    <string>fb16xxxxxxxxxxxx15</string>
  </array>
  </dict>
</array>
<key>FacebookAppID</key>
<string>16xxxxxxxxxxxx15</string>

<key>FacebookDisplayName</key>
<string>Login_AppName</string>

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSExceptionDomains</key>
    <dict>
        <key>facebook.com</key>
        <dict>
            <key>NSIncludesSubdomains</key>
            <true/>
            <key>NSThirdPartyExceptionRequiresForwardSecrecy</key>
            <false/>
        </dict>
        <key>fbcdn.net</key>
        <dict>
            <key>NSIncludesSubdomains</key>
            <true/>
            <key>NSThirdPartyExceptionRequiresForwardSecrecy</key>
            <false/>
        </dict>
        <key>akamaihd.net</key>
        <dict>
            <key>NSIncludesSubdomains</key>
            <true/>
            <key>NSThirdPartyExceptionRequiresForwardSecrecy</key>
            <false/>
        </dict>
    </dict>
</dict>

<key>LSApplicationQueriesSchemes</key>
<array>
  <string>fbapi</string>
  <string>fb-messenger-api</string>
  <string>fbauth2</string>
  <string>fbshareextension</string>
</array>

6. Copy the Bundle Identifier from Xcode and paste it into the Supply us with your Bundle Identifier section of the Quick Start for iOS webpage

7. Disable in-app purchases in the Track App Installs and App Opens section.

Then follow steps 8 and 9 and you may ignore the Track App Installs and App Opens and Let's test out your integration sections in Objective-C.

8. Modify AppDelegate.swift as:

Update (November 7, 2016) with  Xcode 8.1 (Swift 3.0.1):

import UIKit

import FBSDKCoreKit

import FBSDKLoginKit

import FBSDKShareKit

@UIApplicationMain

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    

    func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {

        return FBSDKApplicationDelegate.sharedInstance().application(app, open: url as URL!, sourceApplication: options[UIApplicationOpenURLOptionsKey.sourceApplication] as! String, annotation: options[UIApplicationOpenURLOptionsKey.annotation])

    }

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)

        return true

    }

    func applicationWillResignActive(_ application: UIApplication) {

    }

    func applicationDidEnterBackground(_ application: UIApplication) {

    }

    func applicationWillEnterForeground(_ application: UIApplication) {

    }

    func applicationDidBecomeActive(_ application: UIApplication) {

        FBSDKAppEvents.activateApp()

    }

    func applicationWillTerminate(_ application: UIApplication) {

    }

}

Original solution (January 12, 2016) with Xcode 7.2 (Swift 2.1.1):

import UIKit

import FBSDKCoreKit

import FBSDKLoginKit

import FBSDKShareKit

@UIApplicationMain

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, openURL url: NSURL, sourceApplication: String?, annotation: AnyObject) -> Bool {

        return FBSDKApplicationDelegate.sharedInstance().application(application, openURL: url, sourceApplication: sourceApplication, annotation: annotation)

    }

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        

        FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)

        

        return true

    }

    func applicationWillResignActive(application: UIApplication) {

    }

    func applicationDidEnterBackground(application: UIApplication) {

    }

    func applicationWillEnterForeground(application: UIApplication) {

    }

    func applicationDidBecomeActive(application: UIApplication) {

        FBSDKAppEvents.activateApp()

    }

    func applicationWillTerminate(application: UIApplication) {

    }

}

9. Modify ViewController.swift as:

import UIKit

import FBSDKLoginKit

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        

        let loginButton = FBSDKLoginButton()

        loginButton.center = view.center

        view.addSubview(loginButton)

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

    }

}

10. Build and run the code.

Result with the iPhone simulator:

While the login button is pressed, the Facebook login page is displayed.

You may see this error in the output:

-canOpenURL: failed for URL: "fbauth2:/" - error: "(null)"

Facebook says:

This is an Xcode warning indicating the the canOpenURL: call returned false. As long as you have configured the LSApplicationQueriesSchemes entry in your plist as described above, you can ignore this warning

This error should not appear with iPhone / iPad  devices.

11. The Facebook button becomes Log out after logging in.

12. Try to logout and login again. If the account information is remembered after logout as below:

Then try to clear the Safari cache:

Settings -> Safari -> Advanced (at the bottom) -> Website Data -> Edit -> facebook.com -> Delete

So the Facebook login button is working!!

Additional Information

To manage your Facebook apps online, go to Facebook Developers. Select My Apps and your app name.

If you see this error on iPhone:
App Not Setup: This app is still in development mode, and you don't have access to it. Switch to a registered test user or ask an app admin for permissions.

Try to change to the developer account (Clear Safari cache in Step 12.) or:

Make this app available to the general public or add testers:

The developers of this app have not set up this app properly for Facebook Login?

Related Information:
Facebook SDK for iOS - Getting Started
Facebook SDK and Swift - Get Facebook SDK Version
Facebook SDK for iOS Changelog (SDK Version History)
Facebook Login Review Guide (App review by Facebook is required in some conditions.)
Facebook SDK and Swift - Display User Name and Profile Picture
Facebook SDK and Swift - Create a custom login button programmatically

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