Mac SDK: using latest SDK but ensuring backwards compatibility with earlier deployment target

Question

As always when Apple updates OS X, the latest XCode 4.4 dumps the older (10.6) SDK and I find myself needing to use the 10.7 SDK (or 10.8 I suppose) and setting my deploymen

Answer 1

I check my code by hacking around Availability.h to get the compiler to flag weak-linked symbols as warnings/errors. In my current (Xcode 5/llvm) incarnation, I'm using the code below. It warns whenever I use a symbol introduced in iOS 6.0 or later. I think it's fairly self-explanatory. The macros seem to need updating at each and every SDK update, so tread carefully. Oh, and you loose deprecation warnings too, so I only use this once in a while to double-check my conditional code.

#undef __NSi_6_0
#define __NSi_6_0 deprecated=1.0
#undef __NSi_6_1
#define __NSi_6_1 deprecated=1.0
#undef __NSi_7_0
#define __NSi_7_0 deprecated=1.0

#undef __NSd_6_0
#define __NSd_6_0
#undef __NSd_6_1
#define __NSd_6_1
#undef __NSd_7_0
#define  __NSd_7_0

See also http://iphone.m20.nl/wp/2013/10/xcode-5-and-flagging-weak-linked-unavailable-symbols-from-a-newer-sdk/