Check app store update with SVHTTPClient.

gistfile1.m

    SVHTTPClient *client = [SVHTTPClient sharedClientWithIdentifier:@"APPSTORE"];
    client.basePath = @"http://itunes.apple.com";
    [client GET:[NSString stringWithFormat:@"/lookup?id=%d", APP_STORE_ID] parameters:nil completion:^(id response, NSHTTPURLResponse *urlResponse, NSError *error) {
        NSDictionary *result = [response objectFromJSONDataWithParseOptions:JKParseOptionStrict];
        if (result) {
            NSString *latestVersion = [[result valueForKeyPath:@"results.version"] objectAtIndex:0];
            NSString *appStoreURL = [[result valueForKeyPath:@"results.trackViewUrl"] objectAtIndex:0];
            NSString *appName = [[result valueForKeyPath:@"results.trackName"] objectAtIndex:0];
            NSString *applicationVersion = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"];

            if ([latestVersion compare:applicationVersion options:NSNumericSearch] == NSOrderedDescending) {
                // Show prompts
            } else {
                DLog(@"No need to update");
            }
        }
    }];