What’s the difference between Xcode, Objective-C and Cocoa?

Question

This question pops up quite often here, even if just implicitly when users mistag their iOS questions. So, what’s the difference between Xcode, Objective-C and Cocoa?

Answer 1

A clear mistake is failing to differentiate Xcode from everything else. Xcode is the tool you are using to program in - to edit code, run code, etc. So if you are having trouble with the tool (e.g., the window doesn't show you your code properly, or you're having trouble drawing your interface, etc.), that's an Xcode problem.

If you don't understand why your code doesn't work, you're probably having an Objective-C problem or a Cocoa problem. But you won't necessarily know which.

• It's an Objective-C problem if the root of your trouble is that you don't know how the language works (e.g. you don't know what the asterisk is for, or that declaration is not instantiation, or that messages to nil do not error out but don't do anything either).

• It's a Cocoa problem if you don't grasp the delegate architecture or how a view controller works.

But my experience of the way people pose questions is that you may be ignorant of which of these you are ignorant of. I don't mean you personally, I mean all of us. This can make it difficult to pose the question properly because you don't know what exactly it is that you don't know — if you did, you'd know it and you probably wouldn't be having a problem (you'd be fixing the problem and on to the next thing).