Memory management. Is this single line of code correct?

Question

Do I have a leak with this statement?

//Pass the copy onto the child controller
self.childController.theFoodFacilityCopy = [self.theFoodFacility copy];

My property is set to:

@property (nonatomic, retain) FoodFacility *theFoodFacilityCopy;

The reason I think I have a leak is because copy retains the value and then my dot syntax property also retains the value. Doubly retained...

What is the correct way of writing the above statement?

Thanks

Dan

Answer 1

yes, you do have a leak there.

SomeClass *someObj = [self.theFoodFacility copy];
self.childController.theFoodFacilityCopy = someObj;
[someObj release];

This mirrors the recommended approach for initializing an object too:

SomeClass *someObj = [[SomeClass alloc] init];
self.someProperty = someObj;
[someObj release];

In both cases the first line returns an objects with a retain count of 1, and you treat it identically after that.

Answer 2

You are right. The cleanest way is something like

id temp = [self.theFoodFacitlity copy];
self.childController.theFoodFacilityCopy = temp;
[temp release]

You want to read the apple site on memory management a lot until these rules become second nature.

Answer 3

As mentioned by others, that is indeed a leak. If you expect to be using copies in this way, it’s likely your property should be declared copy instead and the synthesized accessor will do the work for you.

Answer 4

What is the advantage of doing this vs just setting the property to copy?

@property (nonatomic, copy) FoodFacility *theFoodFacilityCopy;