What does 'Nil' represent in Obj-C?

Question

So there 's NULL, which is used for pointers in general, and nil, which is used for object pointers.

Now I see there's also Nil, which is used by lower-level Obj-C runtime functions like class_getProperty.

Is this somehow different from nil philosophically? (yes, I know they're all actually 0)

Why was it even introduced? Or, if Nil was first (which is likely), why was nil introduced?

Exact duplicate, though in different words from http://stackoverflow.com/questions/836601 — balexandre, Aug 19 '09 at 12:53
I agree, it's not a duplicate of that question. [NSNull null] returns an object, where as nil/Nil/NULL are all various forms of 0. — Quinn Taylor, Aug 19 '09 at 16:04

score 8 · Accepted Answer · answered Aug 19 '09 at 12:56

8

Googling "Nil vs nil" found this post http://numbergrinder.com/node/49, which states:

All three of these values represent null, or zero pointer, values. The difference is that while NULL represents zero for any pointer, nil is specific to objects (e.g., id) and Nil is specific to class pointers. It should be considered a best practice of sorts to use the right null object in the right circumstance for documentation purposes, even though there is nothing stopping someone from mixing and matching as they go along.

answered Aug 19 '09 at 12:56

Damien_The_Unbeliever

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Yup, I've seen that page, but I didn't believe it was just for Class pointers. Now, after reading , it seems this really is the case :) – Jaka Jančar Aug 19 '09 at 13:02
What is the class objects and obj c objects where I can use nil,Nil – May 25 '15 at 06:44

What does 'Nil' represent in Obj-C?

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