If my property has no setter (readonly), is it true that UIKit retains the value if it's not NSNumber or NSValue?

Question

I want to figure out in which cases I need to care about memory management when it comes to properties. I wrote down something from a site I don't remember anymore, where they said that if a property has any value other than NSNumber or NSValue, and if it has no setter, then UIKit would autorelease the old value and retain the new one. Although I dont get it why UIKit would set anything if there is no setter (directly to the value, I guess).

Answer 1

If the property is declared as:

@property(retain) NSString *prop;

It will release the old value when you assign a new one.

However, make sure you release it on your dealloc method as well:

- (void)dealloc {
    [prop release];

    [super dealloc];
}

Answer 2

You should (re)read the Memory Management Guide for Cocoa. The memory management rules for properties are the same as for all other objects.