At this time, the newest SDK version that Audacity can build with
is 10.6.  To build Audacity using Xcode 5.1 or newer, you need
to extract the 10.6 SDK from an earlier version of Xcode.

In the instructions below, Xcode 4.3.3 (for the 10.6 SDK) and
Xcode 5.1.1 will be used.  Xcode 6.1.1, 6.3, 6.4.1, and 7.1
have also been verified to work. Xcode 7.2 and later require a 
custom build setting to accept the 10.6 SDK, or to edit 
src\MemoryX.h in the Audacity code. See this topic:
http://forum.audacityteam.org/viewtopic.php?p=303835#p303835 .

1) Download Xcode 5.1.1 or greater and install it to /Applications.
2) Download Xcode 4.3.3 (it includes the 10.6 and 10.7 SDK's despite 
   the downloads page says it only has the 10.7 SDK).
3) Open the DMG in Finder.
4) Right-click the "Xcode.app" bundle and select "Show Package Contents".
5) Navigate down the directories to get to:

   Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/ .

6) Copy the MacOSX10.6.sdk folder to:

   /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/

   Xcode is now ready.

7) Download wxWidgets.  We currently require version 3.0.2, which can be downloaded from:

   http://sourceforge.net/projects/wxwindows/files/3.0.2/wxWidgets-3.0.2.tar.bz2

8) Once the download is complete, untar it (your browser may have already done this):

   tar xf wxWidgets-3.0.2.tar.bz2 .

9) Apply the following fixes to wxWidgets:

   cd wxWidgets-3.0.2
   patch -p0 -i <path to Audacity source>/mac/wxMac_additions/wxMac-3.0.2-fixes.patch .

10) And finally build/install wxWidgets:

   sudo <path to Audacity source>/mac/build_wxwidgets .

You should now be able to build Audacity using either the Xcode application or the
xcodebuild command line tool.

If you need Audacity to use languages other than English, then you'll have to install
the gettext suite of tools (to get the msgfmt command).  The source can be downloaded
from:

   ftp://ftp.gnu.org/gnu/gettext/gettext-latest.tar.gz

Untar it:

   tar xf gettext-latest.tar.gz

And install:

   cd gexttext-latest
   ./configure
   sudo make install