Google OAuth

gistfile1.m

- (void)goGoogle
{
    GPPSignIn *signIn = [GPPSignIn sharedInstance];
    signIn.delegate = self;
    signIn.shouldFetchGoogleUserEmail = YES;
    signIn.clientID = GOOGLE_CLIENTID;
    signIn.scopes = [NSArray arrayWithObjects:kGTLAuthScopePlusLogin,nil];
    signIn.actions = [NSArray arrayWithObjects:@"http://schemas.google.com/ListenActivity",nil];
    [signIn authenticate];
}

- (void)finishedWithAuth: (GTMOAuth2Authentication *)auth
                   error: (NSError *) error
{
    NSLog(@"Received error %@ and auth object %@",error, auth);
    NSString *urlStr = @"https://www.googleapis.com/oauth2/v1/userinfo?alt=json";
    NSURL *url = [NSURL URLWithString:urlStr];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    [auth authorizeRequest:request
              completionHandler:^(NSError *error) {
                  NSString *output = nil;
                  if (error) {
                      output = [error description];
                  } else {
                      // Synchronous fetches like this are a really bad idea in Cocoa applications
                      //
                      // For a very easy async alternative, we could use GTMHTTPFetcher
                      NSURLResponse *response = nil;
                      NSData *data = [NSURLConnection sendSynchronousRequest:request
                                                           returningResponse:&response
                                                                       error:&error];
                      if (data) {
                          // API fetch succeeded
                          output = [[NSString alloc] initWithData:data
                                                          encoding:NSUTF8StringEncoding];
                        
                      }
                      
                      NSLog(@"output:%@",output);
                  }
                  
              }];
}