How to proceed after the Google Authentication in ios App - iphone

Question

How to proceed after the Google Authentication in ios App? When i allow the access for my application. The window appear is "Please copy this code,switch to your application and copy it there:".I dont know how to proceed from here.
This is the code i write
SEL finishedSel = #selector(viewController:finishedWithAuth:error:);
viewController = [[GTMOAuth2ViewControllerTouch
controllerWithScope:scope
clientID:clientID
clientSecret:clientSecret
keychainItemName:nil
delegate:self finishedSelector:finishedSel]autorelease];
-(void)viewController:(GTMOAuth2ViewControllerTouch *)viewController
finishedWithAuth:(GTMOAuth2Authentication *)auth
error:(NSError *)error {
if (error != nil) {
// Authentication failed
} else {
// Authentication succeeded
}
}

Answer 1

after getting the authentication
you can use it to get user data, see this code
NSString *urlStr = #"https://www.googleapis.com/oauth2/v1/userinfo?alt=json";
NSURL *url = [NSURL URLWithString:urlStr];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[self.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] autorelease];
NSLog(#"output:%#",output);
} else {
// fetch failed
output = [error description];
}
}
}];
note you need to add this url in scope https://www.googleapis.com/auth/userinfo.profile

Answer 2

check this link gtm-oauth2
and here is a sample code of finishedWithAuth
(void)viewController:(GTMOAuth2ViewControllerTouch *)viewController finishedWithAuth:(GTMOAuth2Authentication *)auth error:(NSError *)error {
if (error != nil) {
// Authentication failed (perhaps the user denied access, or closed the
// window before granting access)
NSLog(#"Authentication error: %#", error);
NSData *responseData = [[error userInfo] objectForKey:#"data"]; // kGTMHTTPFetcherStatusDataKey
if ([responseData length] > 0) {
// show the body of the server's authentication failure response
NSString *str = [[[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding] autorelease];
NSLog(#"%#", str);
}
self.auth = nil;
} else {
// Authentication succeeded
//
// At this point, we either use the authentication object to explicitly
// authorize requests, like
//
// [auth authorizeRequest:myNSURLMutableRequest
// completionHandler:^(NSError *error) {
// if (error == nil) {
// // request here has been authorized
// }
// }];
//
// or store the authentication object into a fetcher or a Google API service
// object like
//
// [fetcher setAuthorizer:auth];
// save the authentication object
self.auth = auth;
}
}