Re: Compiling for 10.9 through 10.12
Re: Compiling for 10.9 through 10.12
- Subject: Re: Compiling for 10.9 through 10.12
- From: Rich Siegel <email@hidden>
- Date: Thu, 21 Jul 2016 09:45:37 -0400
On Thursday, July 21, 2016, Charles Francoise
<email@hidden> wrote:
I’m trying to find a way to either build for 10.12 from
10.11, or build from 10.12 and run for lower versions.
There are two relevant settings: the SDK and the "Deployment
Target". There used to be multiple options for the SDK, but
lately Xcode has started putting the SDK and the OS version in
lock step, so that Xcode 7 includes only the 10.11 SDK and (I
presume) Xcode 8 includes only the 10.12 SDK. This can be
annoying sometimes, but is not a serious problem in most cases.
The "Deployment Target" setting is more relevant here, I think.
That setting should be set to the lowest OS version which you
plan to support. (In this case, 10.9.)
Even with all of this, you still have to code to the minimum
supported OS. If you have to run on 10.9, you can't call APIs
that don't exist there. Neither the OS nor the tool chain will
stop you from doing so.
In the specific case, I see that clock_gettime() doesn't exist
on 10.11, which means it probably doesn't exist on prior OS
versions either, and that means that you can't call it unless
you do a runtime test to see if it's there. (The address of a
weak-linked function is NULL if the function is unavailable at runtime.)
Good luck,
R.
--
Rich Siegel Bare Bones Software, Inc.
<email@hidden> <http://www.barebones.com/>
Someday I'll look back on all this and laugh... until they
sedate me.
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