I'm in the process of adding a Google Docs interface to my iPhone app, and I'm largely following the example in the GoogleDocs.m file from Tom Saxton's example app.

The objective-c library I'm using is from http://code.google.com/p/gdata-objectivec-client/wiki/GDataObjCIntroduction

The library file used is from gdata-objectivec-client-1.10.0.zip.

This service:username:password method is a slight variant of the one found in the Saxton file GoogleDocs.m starting at line 351:

- (void)service:(NSString *)username password:(NSString *)password
{
   if(service == nil) {
       service = [[[GDataServiceGoogleDocs alloc] init] autorelease];
       [service setUserAgent:s_strUserAgent];
       [service setShouldCacheDatedData:NO];
       [service setServiceShouldFollowNextLinks:NO];
       (void)[service authenticateWithDelegate:self didAuthenticateSelector:@selector(ticket:authenticatedWithError:)];
   }

    // update the username/password each time the service is requested
    if (username != nil && [username length] && password != nil && [password length])
       [service setUserCredentialsWithUsername:username password:password];
    else
       [service setUserCredentialsWithUsername:nil password:nil];   
}

// associated callback for service:username:password: method
- (void)ticket:(GDataServiceTicket *)ticket authenticatedWithError:(NSError *)error
{
    NSLog(@"%@",@"authenticatedWithError called");
    if(error == nil)
        [self selectBackupRestore];
    else {
        NSLog(@"error code(%d)", [error code]);
        NSLog(@"error domain(%d)", [error domain]);
        NSLog(@"localizedDescription(%@)", error.localizedDescription);
        NSLog(@"localizedFailureReason(%@)", error.localizedFailureReason);
        NSLog(@"localizedRecoveryOptions(%@)", error.localizedRecoveryOptions);
        NSLog(@"localizedRecoverySuggestion(%@)", error.localizedRecoverySuggestion);
    }
}

Please note the service:username:password method and the callback compile and run fine. The problem is that the callback is passing a non-nil NSError object. I added an NSLog() for every error reporting attribute of NSError and the (Xcode) log output of a test run is below.

[Session started at 2010-05-27 12:27:16 -0700.]

2010-05-27 12:27:38.778 iFilebox[74596:207] authenticatedWithError called

2010-05-27 12:27:38.779 iFilebox[74596:207] error code(-1)

2010-05-27 12:27:38.780 iFilebox[74596:207] error domain(499324)

2010-05-27 12:27:38.781 iFilebox[74596:207] localizedDescription(Operation could not be completed. (com.google.GDataServiceDomain error -1.))

2010-05-27 12:27:38.782 iFilebox[74596:207] localizedFailureReason((null))

2010-05-27 12:27:38.782 iFilebox[74596:207] localizedRecoveryOptions((null))

2010-05-27 12:27:38.783 iFilebox[74596:207] localizedRecoverySuggestion((null))

My essential question is in the error reporting. I was hoping the localizedDescription would be more specific of the error. All I get for the error code value is -1, and the only description of the error is "Operation could not be completed. (com.google.GDataServiceDomain error -1.". Not very helpful. Does anyone know what a GDataServiceDomain error -1 is? Where can I find a full list of all error codes returned, and a description of what they mean?