Objective C release, autorelease, and data types

Question

I\'m new to memory managed code but I get the idea pretty well.

On taking my app through the leaks tool in XCode, I noticed I only had to clean up my custom objects,

Answer 1

Cocoa uses certain naming conventions. Anything that starts with alloc, new, or copy returns something with a retainCount of 1 and you are required to release. Anything else that a function returns has a balanced retainCount (it might be held by something else, or it might be retained and out released).

So:

NSMutableArray *removals = [NSMutableArray new];

Has a retainCount of 1, and:

NSMutableArray *removals = [NSMutableArray arrayWithCapacity:99];

or

NSMutableArray *removals = [NSMutableArray array];

Don't since the methods are not prefixed with alloc, new or copy. This is all spelled out in the memory management documentation. In particular:

You take ownership of an object if you create it using a method whose name begins with “alloc” or “new” or contains “copy” (for example, alloc, newObject, or mutableCopy), or if you send it a retain message. You are responsible for relinquishing ownership of objects you own using release or autorelease. Any other time you receive an object, you must not release it.