Objective C: Memory Leak in non-void instance method

I am getting another memory leak in a non-void instance method that returns a object of class NSMutableArray.

Can someone advise me开发者_JAVA百科 on how I can fix this leak? I tried to release 'userFollowings' at the end of the method but it's still reporting a leak.

When your are to return an object from a method in which you have either initialized it or retained it, it is common practice to return it autoreleased. That way, the user receiving the object doesn't have to worry about releasing it. So, your final line of code should look like this:

return [userFollowing autorelease];

It probably wouldn't hurt to read a little from the Memory Management Programming Guide to catch up on memory management rules such as this, and there are plenty of other helpful resources out on the web and on this site.

There are a set of conventions used by Cocoa programs that make memory management much less error prone. When a method returns an object, the code that calls it needs to know if it owns it or not.

What it boils down to is that if you are writing a method that returns an object and that method doesn't convey ownership upon the caller by being named something like new, alloc, copy, etc., you need to autorelease it before you return it.

That's what the message you are getting is talking about - "Object returned to caller as an owning reference" means that you're conveying ownership on the calling code. The problem is that your method name indicates otherwise.

If I were to call your method and needed to hang onto the object, I'd call retain on it so that I owned it. I need to do this because your method name implied I wasn't the owner. So long as you are returning an autoreleased object, that's correct. But if you don't autorelease the object, it will end up with a retain count of 2 - once when you allocated it and once when I retained it. When I finally get round to releasing it, it will still have a retain count of 1, and will never be deallocated from memory, resulting in a memory leak.

The problem is that userFollowings never gets released. Try ending with

return [userFollowings autorelease];

Try this:

   NSMutableArray* userfollwings = [[[NSMutableArray alloc] init] autorelease]