Writing Objective-C has so many use cases by so many people. We felt that needing your Mac on you to learn or experiment with the language was a hassle, there had to be a better way. So we made Codebox, an Objective-C interpreter for iOS that allows for writing, saving and running of Objective-C code, right from your iPad or iPhone! It's similar to Swift playgrounds, but on a mobile device for Objective-C. All of the code written is actually run natively by the device at runtime, with access to almost all iOS features and APIs.
We feel many different people have something to gain from this, including people learning the language for the first time, or even experienced developers who want to prototype on the go.