Retrieve JSON in iOS 6. It's that simple.

getJSONObjectiveC

Sinatra:
get '/messages' do
    content_type :json
    
    messages = []
    all = $redis.lrange("messages", 0, $redis.llen("messages"))
    all.each do |message|
        messages.push( message )
    end
    { :result => "success", :messages => messages }.to_json
end

Objective-C:
-(void)getMessages {
    NSURL *url = [NSURL URLWithString:@"http://localhost:9292"];
    AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:url];
    [httpClient setParameterEncoding:AFJSONParameterEncoding];
    NSMutableURLRequest *request = [httpClient requestWithMethod:@"GET"
                                                            path:@"messages"
                                                      parameters:nil];

    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        NSLog(@"messages: %@", [JSON valueForKeyPath:@"messages"]);
    } failure:nil];

    [operation start];
}