可可触摸-内存管理

Question

I am a former java programmer, and I am having some troubles managing the memory on cocoa touch. In fact, I think I got the retain/release trick, but still I am not sure I got it right.

For example, I am creating and adding a subview to the main window:

aViewController=[[AViewController alloc]init];//aViewController is (nonatimic,assign), so retaincount = 1 after this line?
[self.window addsubview aViewController];
[aViewController release];//retaincount=0?

And in aViewController I have an IBAction:

[self.view removeFromSuperView];

How can I be sure the object aViewController gets completely 'deleted' and memory released after I removed it from superview (think that controller as a graphic-heavy view controller)?

Also, generally, is there a way to be sure an object is deallocated? I am aware that if I ask ownership of an object I have to release it at a certain point, but what if I just want the object's pointer to be null at a certain point(not basing on the retaincount)? Should I call dealloc directly? I find sometimes very confusing to keep under control the retain/release mechanism.

If someone could give me a quick breakdown to make my mind 'click', i would be extremely grateful. Thanks.

Answer 1

The short answer is you shouldn't worry about when an object gets deallocated (unless you are debugging a memory management problem). You should just worry about ensuring that if your code retains, copies or inits an object, it releases or autoreleases it. By doing so you will ensure reference counts are properly maintained and hence deallocation will be managed for you.

Leave the task of deciding when to dealloc an object to the runtime. Never call dealloc directly unless you are calling the super classes dealloc method at the end of your objects dealloc method.

Answer 2

Also, don't even look at the retain count property of an object. Various pieces of the framework manipulate those too during the lifetime of the object, and you'll see that number move around seemingly at random. It'll just drive you nuts.

The really important thing is to make sure you've got the objects retained that would be a problem if they went away suddenly, and released when you're okay with them going away suddenly.

Answer 3

aViewController=[[AViewController alloc]init];

retainCount is 1

[aViewController removeFromSuperView];

retainCount is 2 (adding the view increments the retainCount)

 [aViewController release];  

retain count decrements to 1;

 [aViewController removeFromSuperView];  

retain count decrements to 0;
Now the dealloc method will be called the allocated memory will be freed. This is what have understood please correct me if i am wrong i always find difficulties during memory management.