"I once told an Objective-C joke, but nobody got the message."
Many of us are being introduced with the concept of networking in iOS and Objective-C by playing with
NSURLConnection. It's a base class for making any outgoing HTTP connection. However, after using it several times in a project, you may start building your personal networking library, of course, under the hood; it's still the same NSURLConnection, but most likely, you would write your own wrappers for it with additional bells and whistles. In addition, while using it, you may experience different bugs, glitches, and performance issues. Also, while using it in different projects, you will probably modify the code, find and fix bugs in it, but you will experience a lot of hassles in maintaining a "one codebase" of such a homegrown library.
So my personal opinion is "Don't re-invent the wheel. Don't re-invent a bicycle. Unless you really need a very custom one, with a big front wheel (as shown in the next figure), which might happen only in 1 percent of cases."
Try to keep things simple. In our case, the working bicycle can be a library called AFNetworking, which is a very useful networking library for iOS and OS X. The framework is built on top of Apple's Foundation technologies such as NSURLConnection, NSOperation, and others. It has a modular architecture and a well-designed API, which is quite easy to use. While being simple and easy-to-use, it also supports block-based programming, file uploads, reachability, and lots of other useful tasks that any developer might need. It is used by thousands of app developers and is highly maintained.
Now RestKit itself is a framework for implementing clients of RESTful web services, and feels like AFNetworking is on steroids. It provides a simple interface to build network communication while mapping HTTP requests and responses. Additionally, it has a powerful object-mapping engine that seamlessly integrates with the Core Data. It has an elegant, well-designed, fully documented, and fully tested set of APIs magically allowing easy accessing and modeling RESTful resources.
It greatly simplifies the application development by providing a solution by interconnecting your application's data model with JSON or XML documents, provided by a web service you are communicating with. It shifts a lot of logic for making requests and mapping the data to the library, thus giving a developer the ability to keep an application code simpler and less cluttered. It speeds up the development process by giving solutions and patterns for common problems that one can face, such as working with Core Data and doing network-related coding.
When thinking whether to use a RestKit library in your next project, consider a few things:
Not every API will work with a RestKit library, especially the ones that follow the RPC (Remote Procedure Call) paradigm.
Your backend web-service API is more or less RESTful. You can describe interactions with your web application with the CRUD (Create, Read, Update, and Delete) operations on resources.
"Don't use a sledgehammer to crack a nut." If you just need a one-time request to a simple JSON in your app, reconsider using a RestKit library in favor of using something simple, such as AFNetworking.
While developing a library, think if you can minimize a footprint of it and exclude dependencies on big third-party libraries, such as RestKit.