Alloc a new objective C object to a retained property?

Question

Sorry for asking a totally basic question, but if I have a synthesized property that is retained.

 self.myProperty = [[NSObject alloc] init];

will cause a memory leak?

So am I correct in thinking that I need to do

self.myProperty = [[NSObject alloc] init];
[self.myProperty release];

in order to balance? Because that seems dumb.

Answer 1

Standard practice would be to use autorelease in that situation. So:

self.myProperty = [[[NSObject alloc] init] autorelease];

This is because init returns a retained object, and since your property also retains it, you'll have to release it.

Edited to add: @walkytalky makes a good point in the comments that it is actually alloc that retains the object, init just returns it.

Answer 2

Here is a thread that you will find helpful.

You are correct. Without ARC, any property that is retained needs to be released as well.

You can also do:

self.myProperty = nil;

From the docs:

retain

Specifies that retain should be invoked on the object upon assignment.

The previous value is sent a release message.

Answer 3

Another (more verbose) technique is to do:

NSObject *o = [[NSObject alloc] init]; //retain count 1
self.myProperty = o;                   //retain count 2
[o release];                           //retain count 1

Personally though, I'd probably just use autorelease as in the first example above.

Answer 4

With ARC enabled, xcode will handle alle the memory management. When not using ARC be sure to release it in the dealloc method.