How much of a transition is programming Java to iPhone apps?

Question

I'm a highly skilled Java dev contemplating learning iPhone development. Mac only dev aspects aside, how much of a leap would learning the mobile application stack be? Sure I understand that its closer to C in how one should approach it, and with that comes memory management and so on.

My queries would also include

1. How well is OOP/OOAD supported?
2. Is there some API(s) which enable unit testing?

I'd encourage those who answer to quote external sites and references to help elaborate the detail

Answer 1

The development language is Objective-C, which is pure C with a very thin object wrapper over the top. They syntax is kind of weird looking, but it's pretty easy to get to grips with if you know C once you get over the message calls - myself I have a solid C background and only started picking up Objective-C a month or two so back but I'm finding it really rather pleasing - more so than C++.

The difficulty you're going to have if you have only coded Java is pointers and memory management. Memory management isn't conceptually hard as it's simply (!) a question of keeping track of what you are allocating and releasing, plus XCode seems to come with good tools for detecting leaks (although I haven't used these in anger yet) - and as iPhone programs are relatively small it's not like coding a big system program where this can be extremely tough. The major conceptual difficulty you are likely to have is simply getting your head around pointers as they are used extensively (as in just about on every line of code) and you do need to grok these completely. One of Joel's reoccuring themes on the podcast is the difficulty some coders get using pointers, so I'd recommend you take that carefully and possibly pick up a good book - perhaps the original K&R.

Someone may like to correct me, but although the Cocoa API appears excellent, there seem to be few libraries available outside the framework (unlike C++ or Java). For instance I had to add my own queue and stack classes - although the NSMutableArray makes that extremely easy.

All in all though I'm certainly finding it one the most fun platforms to play with I've used for a while.

Answer 2

A few months ago I was a Java web programmer who hadn't touched C since college. Now I've got one iPhone app completed (for my day job, stuck in the bureaucracy there so it's not in the app store yet) and my second app nearing completion.

To answer your question the biggest hurdles are understanding the conventions (Delegate pattern, Categories, etc.), getting a grasp on memory management, and working with XCode (a good IDE but definitely steps behind Eclipse and IntelliJ).

I also think the documentation in the Apple Developer Center website is well-written, and a good developer can get up and running quickly.

To more specifically answer your question, I haven't tried Unit Testing yet but I think the OOP is great - my domain objects in my iPhone apps are as robust and powerful as those I've written in Java.