Question

In a project with garbage collection set to required: If I instantiate an object in Interface Builder and add it to the XIB/NIB, do I need to assign this object to some outlet to avoid it being garbage-collected, or is that taken care through some other means?

Answer 1

I just built a small test project. With GC, the object created through Interface Builder gets collected soon afterwards. So the answer to the question is: yes.

I did a bit more testing:

With classical reference counting this does not happen. This is possibly what one would expect, but it is also probably a memory leak. Not sure here. (If not, and the NIB/XIB-contained objects get released when the file’s owner is release, e.g., then this would constitute a significant difference in behavior between GC and classical RC.)

With ARC enabled, I did not find a way to tell. There is probably some function I could put a breakpoint on and wait for the specific object fly by.

Edit:

I reviewed the documentation, and it states it quite clearly. Missed that the first time around:

You typically need strong references to top-level objects to ensure that they are not deallocated; you don’t need strong references to objects lower down in the graph because they’re owned by their parents, and you should minimize the risk of creating strong reference cycles.

From: Resource Programming Guide, Managing the Lifetimes of Objects from Nib Files