Objective C autorelease

Hello I do not fully understand the autorelease function call in obj-C.

@interface A{
id obj;
}

@implementation A

-(void)myMethod;
{
obj = [BaseObj newObj];           //where newObj is a method like :[[[BaseObj alloc]init]autorelease];
}

-(void)anotherMehtod;
{
[obj someMeth];                     //this sometimes gives me EXC_BAD_ACCESS
}

@end

So to solve this I put a开发者_开发问答 retain. Now do I need to release this object manually if i retain it?

If you are the owner of an object - is your responsibility to release it.

You become owner of an object if you've done at least one of the following:

• instantiated it through alloc
• passed retain
• passed copy

For more details read Object Ownership and Disposal

Yes. The rule is, if you retain an object, you are also responsible of releasing it in iOS.

Like all other static methods in Obj-C [BaseObj newObj] only exists in your method -(void)myMethod at the end of this method (roughly) obj gets -release message from autorelease pool.

If you want to preserve this object - use [[BaseObj newObj] retain] or [BaseObj alloc] init] and release it in -dealloc or when you has to.

For example:

@interface A{
  id obj;
}

@implementation A

-(void)myMethod
{
  [obj autorelease];
  obj = [[BaseObj newObj] retain];           //where newObj is a method like :[[[BaseObj alloc]init]autorelease];
}

-(void)anotherMehtod;
{
  [obj someMeth];                     //this sometimes gives me EXC_BAD_ACCESS
}

-(void)dealloc
{
  [obj release];
  [super dealloc];
}

@end