I try to get the hang of it, but for now both seem the same thing to me. However, Xcode allows to create an Consol开发者_开发技巧e App with choice of using "Core Foundation" or just "Foundation". Maybe someone can point out the differences.

Core Foundation is the C-level API, which provides CFString, CFDictionary and the like.

Foundation is Objective-C, which provides NSString, NSDictionary, etc.

CoreFoundation is written in C while Foundation is written in Objective-C;

Foundation has a lot more classes;

CoreFoundation is the common base of Foundation and Carbon.

A little history

Ref: http://ridiculousfish.com/blog/posts/bridge.html

Mac OS 9 and NEXTSTEP merged to create Mac OS X. And Core Foundation was created as a common ground for classic Mac toolbox and OPENSTEP(Which I believe is the toolbox for NEXTSTEP).

Classic Mac toolbox evolved and became Carbon.

OPENSTEP evolved and became Cocoa which includes Foundation.

So I conclude that, Core Foundation has much longer history and it is the foundation of Foundation. Since Foundation is kind of high-level and modern, I will stick to it unless I need to handle some historic issues which requires Core Foundation.