Native Google Reader iPhone Application

I am currently in the process of building a native Google Reader iPhone application similar to the successful application "Reeder for iPhone", however, with a full Twitter clie开发者_运维百科nt inbuilt as well.

I have finished the Twitter client and am now struggling to start the Google Reader client. I've browsed through multiple documents and have taken a look at the gdata-objective-client samples, yet I still can't seem to understand what I have to do to accomplish the same functionality as Reeder does.

Basically I want to be able to present the user with a login screen. The user then submits their credentials and the access token and all of that are done behind scenes, like they do with Twitter's xAuth. I then want to push a view controller that shows a UITableView with all the current unread feeds. When the user clicks the UITableViewCell a detailed view is respectively pushed containing the posts content.

Is this possible and if so, how do I go about implementing these features? I would appreciate it if people posted "code snippets" and actually show how they achieve the implementations.

Thanks in advance!

EDIT: It has been brought to my attention that the google app engine isn't needed. The question however, still remains the same. How would I implement Google Reader into my application?

It was so simple. For all those wondering, to connect to Google Reader API, I did the following.

/*  Google clientLogin API:
     Content-type: application/x-www-form-urlencoded
     Email=userName
     Passwd=password
     accountType=HOSTED_OR_GOOGLE
     service=xapi
     source = @"myComp-myApp-1.0"
     */

    //define our return objects
    BOOL authOK;
    NSString *authMessage = [[NSString alloc] init];
    NSArray *returnArray = nil;
    //begin NSURLConnection prep:
    NSMutableURLRequest *httpReq = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:GOOGLE_CLIENT_AUTH_URL] ];
    [httpReq setTimeoutInterval:30.0];
    //[httpReq setCachePolicy:NSURLRequestReloadIgnoringCacheData];
    [httpReq setHTTPMethod:@"POST"];
    //set headers
    [httpReq addValue:@"Content-Type" forHTTPHeaderField:@"application/x-www-form-urlencoded"];
    //set post body
    NSString *requestBody = [[NSString alloc] 
                             initWithFormat:@"Email=%@&Passwd=%@&service=reader&accountType=HOSTED_OR_GOOGLE&source=%@",
                             gUserString, gPassString, [NSString stringWithFormat:@"%@%d", gSourceString]];

    [httpReq setHTTPBody:[requestBody dataUsingEncoding:NSASCIIStringEncoding]];

    NSHTTPURLResponse *response = nil;
    NSError *error = nil;
    NSData *data = nil;
    NSString *responseStr = nil;
    NSArray *responseLines = nil;
    NSString *errorString;
    //NSDictionary *dict;
    int responseStatus = 0;
    //this should be quick, and to keep same workflow, we'll do this sync.
    //this should also get us by without messing with threads and run loops on Tiger.
    data = [NSURLConnection sendSynchronousRequest:httpReq returningResponse:&response error:&error];

    if ([data length] > 0) {
        responseStr = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
        //NSLog(@"Response From Google: %@", responseStr);
        responseStatus = [response statusCode];
        //dict = [[NSDictionary alloc] initWithDictionary:[response allHeaderFields]];
        //if we got 200 authentication was successful
        if (responseStatus == 200 ) {
            authOK = TRUE;
            authMessage = @"Successfully authenticated with Google. You can now start viewing your unread feeds.";
        }
        //403 = authentication failed.
        else if (responseStatus == 403) {
            authOK = FALSE;
            //get Error code.
            responseLines  = [responseStr componentsSeparatedByString:@"\n"];
            //find the line with the error string:
            int i;
            for (i =0; i < [responseLines count]; i++ ) {
                if ([[responseLines objectAtIndex:i] rangeOfString:@"Error="].length != 0) {
                    errorString = [responseLines objectAtIndex:i] ;
                }
            }

            errorString = [errorString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
            /*
             Official Google clientLogin Error Codes:
             Error Code Description
             BadAuthentication  The login request used a username or password that is not recognized.
             NotVerified    The account email address has not been verified. The user will need to access their Google account directly to resolve the issue before logging in using a non-Google application.
             TermsNotAgreed The user has not agreed to terms. The user will need to access their Google account directly to resolve the issue before logging in using a non-Google application.
             CaptchaRequired    A CAPTCHA is required. (A response with this error code will also contain an image URL and a CAPTCHA token.)
             Unknown    The error is unknown or unspecified; the request contained invalid input or was malformed.
             AccountDeleted The user account has been deleted.
             AccountDisabled    The user account has been disabled.
             ServiceDisabled    The user's access to the specified service has been disabled. (The user account may still be valid.)
             ServiceUnavailable The service is not available; try again later.
             */

            if ([errorString  rangeOfString:@"BadAuthentication" ].length != 0) {
                authMessage = @"Please Check your Username and Password and try again.";
            }else if ([errorString  rangeOfString:@"NotVerified"].length != 0) {
                authMessage = @"This account has not been verified. You will need to access your Google account directly to resolve this";
            }else if ([errorString  rangeOfString:@"TermsNotAgreed" ].length != 0) {
                authMessage = @"You have not agreed to Google terms of use. You will need to access your Google account directly to resolve this";
            }else if ([errorString  rangeOfString:@"CaptchaRequired" ].length != 0) {
                authMessage = @"Google is requiring a CAPTCHA response to continue. Please complete the CAPTCHA challenge in your browser, and try authenticating again";
                //NSString *captchaURL = [responseStr substringFromIndex: [responseStr rangeOfString:@"CaptchaURL="].length]; 
                //either open the standard URL in a browser, or show a custom sheet with the image and send it back...
                //parse URL to append to GOOGLE_CAPTCHA_URL_PREFIX
                //but for now... just launch the standard URL.
                //[[NSWorkspace sharedWorkspace] openURL:[NSURL URLWithString:GOOGLE_CAPTCHA_STANDARD_UNLOCK_URL]];         
            }else if ([errorString  rangeOfString:@"Unknown" ].length != 0) {
                authMessage = @"An Unknow error has occurred; the request contained invalid input or was malformed.";
            }else if ([errorString  rangeOfString:@"AccountDeleted" ].length != 0) {
                authMessage = @"This user account previously has been deleted.";
            }else if ([errorString  rangeOfString:@"AccountDisabled" ].length != 0) {
                authMessage = @"This user account has been disabled.";
            }else if ([errorString  rangeOfString:@"ServiceDisabled" ].length != 0) {
                authMessage = @"Your access to the specified service has been disabled. Please try again later.";
            }else if ([errorString  rangeOfString:@"ServiceUnavailable" ].length != 0) {
                authMessage = @"The service is not available; please try again later.";
            }

        }//end 403 if

    }
    //check most likely: no internet connection error:
    if (error != nil) {
        authOK = FALSE;
        if ( [error domain]  == NSURLErrorDomain) {
            authMessage = @"Could not reach Google.com. Please check your Internet Connection";
        }else {
            //other error
            authMessage = [authMessage stringByAppendingFormat:@"Internal Error. Please contact notoptimal.net for further assistance. Error: %@", [error localizedDescription] ];
        }
    }
    //NSLog (@"err localized description %@", [error localizedDescription]) ;
    //NSLog (@"err localized failure reasons %@", [error localizedFailureReason]) ;
    //NSLog(@"err code  %d", [error code]) ;
    //NSLog (@"err domain %@", [error domain]) ;


    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Authentication" message:authMessage delegate:self cancelButtonTitle:@"Okay" otherButtonTitles:nil];
    [alertView show];
    [alertView release];

    [gUserString    release];
    [gPassString    release];
    [gSourceString  release];

    [authMessage    release];

}

}

Obviously I used my own delegates and such, but that is the overall want/feel that I brought to my application.

I'm currently working on pulling the unread feeds/items into a UITableView to display in my RootViewController. I'll update this with more information.

Thanks to all those that tried to help :D

THANK YOU. I knew there was a simple way to log in, but I was having a horrible time figuring it out. Btw for those of you who are copying/pasing the the0rkus's code above - you'll get a few errors. To test it out I added:

NSString *gUserString = @"yourlogin@gmail.com";
NSString *gPassString = @"yourpassword";
NSString *GOOGLE_CLIENT_AUTH_URL = @"https://www.google.com/accounts/ClientLogin?client=YourClient";
NSString *gSourceString = @"YourClient";

Google it, there are lots of blogs out there that describe how to use the Google Reader API. Here's a decent starting point: http://mindsharestrategy.com/google-reader-api-a-brief-tutorial/