Google Sign-In quick migration guide

If you have an existing iOS application using Google+ Sign-In, this guide shows you the bare minimum changes necessary to migrate your application to Google Sign-In.

1. Changes for the ViewController header file

1. Add the Google Sign in 2.0 interface:

   #import <GoogleSignIn/GoogleSignIn.h>
   

2. Make the class a delegate to receive Sign-In messages:

   @interface ViewController : UIViewController <GIDSignInDelegate, GIDSignInUIDelegate>
     // ... Typically, you'll add buttons here
   @end
   

2. Changes for the ViewController implementation file

1. Import Google sources:

   #import <GoogleSignIn/GoogleSignIn.h>
   

2. Initialize the GIDSignIn shared instance. Request the profile and email scopes.

   @implementation ViewController
   - (void)viewDidLoad {
     [super viewDidLoad];
   
     GIDSignIn* signIn = [GIDSignIn sharedInstance];
     if (self.fetchEmailToggle.isEnabled) {
       signIn.shouldFetchBasicProfile = YES;
     }
     signIn.clientID = kClientId;
     signIn.scopes = @[ @"profile", @"email" ];
     signIn.delegate = self;
     signIn.uiDelegate = self;
     self.statusField.text = @"Initialized auth2...";
   }
   

3. Implement the delegate methods:

   - (void)signIn:(GIDSignIn *)signIn didSignInForUser:(GIDGoogleUser *)user withError:(NSError *)error {
       // Perform any operations on signed in user here.
     self.statusField.text = @"Signed in user";
   }
   - (void)signIn:(GIDSignIn *)signIn didDisconnectWithUser:(GIDGoogleUser *)user withError:(NSError *)error {
       // Perform any operations when the user disconnects from app here.
       self.statusField.text = @"Disconnected user";
   }
   

4. Map buttons to Auth operations:

   - (IBAction)signInClicked:(id)sender {
     self.statusField.text = @"Clicked sign in!";
     [[GIDSignIn sharedInstance] signIn];
   }
   - (IBAction)signOutClicked:(id)sender {
     self.statusField.text = @"Clicked sign out!";
     [[GIDSignIn sharedInstance] signOut];
   }
   - (IBAction)disconnectClicked:(id)sender {
     self.statusField.text = @"Clicked disconnect!";
     [[GIDSignIn sharedInstance] disconnect];
   }
   - (IBAction)emailToggled:(id)sender {
     if (self.fetchEmailToggle.isEnabled) {
       [GIDSignIn sharedInstance].shouldFetchBasicProfile = YES;
     }else{
       [GIDSignIn sharedInstance].shouldFetchBasicProfile = NO;
     }
   }
   

3. Changes for the AppDelegate implementation file

1. Import GoogleSignIn:

   #import <GoogleSignIn/GoogleSignIn.h>
   

2. Handle the URL from OAuth responses:

   - (BOOL)application:(UIApplication *)application openURL:(NSURL *)url
         sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
     return [[GIDSignIn sharedInstance] handleURL:url sourceApplication:sourceApplication
         annotation:annotation];
   }
   

4. Add URL types

In your project's Info tab, add two URL types.

• In one URL type, specify a unique string in the Identifier field, and specify your client ID in reversed order in the URL Schemas field. For example, if your client ID for iOS is CLIENT_ID_CODE.apps.googleusercontent.com, then specify com.googleusercontent.apps.CLIENT_ID_CODE in the URL Schemas field.
• In the other URL type, specify a unique string in the Identifier field, and specify your app's bundle identifier in the URL Schemas field.