Question

When an array is created in Objective-C using alloc init, how is the memory managed when objects are added to the array?

I would like to know how this relates to C when you create an array and malloc, the allocated size needs to be the size of the expected array or the array memory needs to be reallocated.

How do these relate or what is a good way to understand the way the C code works.

Does the objective-c arrays memory get handled internally when objects are added or how does this work?

Answer 1

An Objective-C array follows the same memory management rules as other Objective-C objects. If you allocate it, you’ll need to release it.

C arrays and Objective-C arrays are similar in concept, but implemented quite differently. A C array is a contiguous block of memory with very little other than a language construct governing how you use it. Objective-C arrays are objects with significant built-in functionality. They dynamically resize themselves (if they’re mutable) to accomodate added elements. They properly retain and release the objects that they store. They can sort themselves, filter themselves, insert objects, delete objects, etc. You should make no assumptions about how they’re implemented.

Apple’s documentation should give you a much better idea of what’s possible with Objective-C arrays (and while you’re at it, look at the other collection classes too). Start reading here:
Collections Programming Topics