Test-Driven iOS Programming

Test-Driven iOS Programming has grown out of my own frustration trying to learn how to develop an iPad/iPhone app. There is no shortage of material covering every aspect of iOS programming, but I haven't found anything yet that seemed to allow me to learn efficiently. This guide aims to be the resource that would have helped me get into iOS development quickly. I would characterize that background as someone who

• has done quite a lot of programming, including some C
• has done some object-oriented programming (mostly in Python, but I don't think the lanuage matters too much)
• is a believer in (non-dogmatic) test-driven development
• prefers to write code in a text editor (specifically Emacs, but it could as easily have been vi, or anything else)
• has tended to avoid GUI programming to date (but realises this is a hurdle that needs to be overcome).

The closer you are to this sort of (dinosaur) profile, the more helpful I think this guide is likely to be, though the only specific that matters is that you have some experience of C, even if it's old. Over the last month or so, I have finally started making progress developing a real application under iOS after two or three previous unsuccessful attempts. The previous attempts were based on (1) working through Apple documents and online material and (2) working through Matt Neuberg's iOS 4 and iOS 5 books. The problem with both of those, for me, was that they were really slow and kept me out of my confort zone from the very beginning. My more successful approach has been as follows:

1. Choose a real application to build.
2. Start with the algorithmic parts of it (i.e., not the GUI)
3. Write the core of the program first in a language you already know, including developing tests.
4. Translate, pretty-much class-by-class, method-by-method, function-by-function and test-by-test, the same code into Objective-C in XCode.
5. If the application will use graphics (drawing, as opposed to just a GUI) generate the core graphical content (not GUI elements, but actual drawing) in a familiar language (again, Python in my case).
6. Translate that graphics code to Objective-C too (probably still just generating file-based output at this stage).
7. Only once quite a lot is working, start actually building the GUI. By the time, you will have learnt enough about XCode, Objective C and the Foundation libraries that in order to do the GUI stuff you really need to learn onlythe GUI stuff---assembling user interfaces, drawing on canvases and intercepting touch events, and you have a solid body of working code to use to generate the content.

Of course, you will need lots of other reference material, but I'll try to explain how and where to get this as we go along. You might well still want to have one or more of the big iOS development books around for reference and digging into topics, but as long as you have an internet connection, you should be able to get a long way even without those.