I've only used Java and Ruby for so long that I'm really not enjoying keeping track of my own memory again. It's not that I can't do it, I can. I just don't want to.
Any special tricks, libraries, or anything else you've learned for dealing with memory in iApps, lay it on me here.
It's a pain. I'd say the most important habit to get into is running the memory tool after you write every significant piece of code, at least until you get a feel for how things work.
And be sure to run it on the device, not the simulator. The two handle some memory situations differently.
Also, don't be surprised if you see memory usage go up when the system is caching an asset. If I recall correctly, I spent a lot of time trying to figure out why a bitmap wasn't going away. I didn't have my talons in it anymore, but the OS thought it might be a good idea to cache it until memory ran low.
Here's a great blog post on how icky iPhone memory management can be. Some good ideas in there.
I haven't done this, but I know that Mono has been ported to the iPhone, which means that you can write iPhone applications in .Net (C#, VB.Net etc.), and not have to worry about memory management.
It's really very, very easy. Stop worrying about retain counts and, for goodness sake, never call the "retainCount" method on an object. It's useless.
If you call a method with "alloc", "new", or "copy" anywhere in its name, or you call the "retain" method, you own that object. You're responsible for relinquishing that ownership when you're done with it.
To do that, call "release" if you don't still need to return a reference to the object or "autorelease" if you do.
The documentation on the subject is unequivocal. It's not difficult.
They just had a Dot Net Rocks show on this
http://www.dotnetrocks.com/default.aspx?showNum=454
They mention both the mono project and the fact that Objective C 2.0 will have better memory managemnet capabilities. Other than that, it sucks.
Edit:fixed bad typos
It can be awkward coming from Java or Python (I did), but once you get used to it, it's just natural. You own objects created with alloc or copy and must release them, anything else not. Most of the time you will be creating autoreleased objects (collections, strings).
It's not really that difficult. Here's some rules of thumb that will go a LONG way.
These are really rough rules of thumb, and I'm sure everyone can come up with exceptions to these rules, but these will go a long way toward getting you allocating and releasing memory the right way.
For the rest of the way, run your code with the Leaks instrument often. Fix problems AS YOU FIND THEM. It's much easier to fix it now than it is to fix it in a month, when you don't remember why you wrote the code that way.
And finally... it's rare, but Apple code DOES sometimes leak. The Leaks instrument should tell you exactly what is being leaked. If it doesn't look like something you are doing, it's POSSIBLE that it's not. As a concrete example: Core Data for the iPhone leaks small amounts of RAM upon (I think) creating a new ManagedObjectContext. Might be when you do a fetch, though, I can't remember right off the top of my head.
I would highly recommend getting Beginning iPhone Development: Exploring the iPhone SDK.
Another key thing to look into is getting the Clang Static Analyzer setup. It analyzes your code and can catch many common memory leaks as well as potential logic issues. Apple has contributed to this analyzer heavily and will be looking to integrate it into future releases of X-Code ;)
Forget all this, don't bother reading anyones comments/answrers, just read the very simple Memory Management Rules. Its only a dozen sentences for heavens sake, you can read it in one minute.