At this time, Audacity is usually built with the 10.7 SDK.  This is to give
compatibility with older versions of MacOSX.
To build Audacity using Xcode 5.1 or newer, you need to extract the 10.7 SDK
from an earlier version of Xcode.

In the instructions below, Xcode 4.3.3 (for the 10.7 SDK) and Xcode 8.1 will
be used and can be downloaded from https://developer.apple.com/download/more/ 
(requires Apple ID to login).

Fuller instructions that cover 
   * Using other Xcodes
   * Optional signing of DMGs
   * Applying wxWidgets patches one by one
can be found on our wiki at http://wiki.audacityteam.org/wiki/Building_On_Mac

1) Download Xcode 8.1 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 MacOSX10.7.sdk folder to:

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

7) Change the MinimumSDKVersion key value in 
   /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Info.plist 
   to 10.7

   Xcode is now ready.

8) Download audacity patched wxWidgets 3.1.1 zip from the audacity copy of the 
   wxWidgets project: 
      https://github.com/audacity/wxWidgets/tree/v3.1.1

   it's the green "clone or download" button on the right.
   To clone into a new directory "wxWidgets":
      git clone --recurse-submodules https://github.com/audacity/wxWidgets/tree/v3.1.1 wxWidgets
   then checkout the v3.1.1 branch:
      cd ./wxWidgets
      git checkout v3.1.1

   Don't be tempted to use Widgets already installed by a package manager such 
   as Homebrew because this will cause problems.   

   As of 16-Apr-2018 we haven't yet applied any Audacity specific patches
   to the official wxWidgets 3.1.1 branch, so currently it is the same.

9) Once the download is complete, unzip it:

   unzip wxWidgets-audacity-v3.1.1.zip

10) Change directory to the folder wxWidgets was extracted to then build/install 
    wxWidgets:

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

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

* Change directory to <path to Audacity source>/mac
* Optionally, if you have built before, clean the Debug build with:

  xcodebuild clean

* If you have built the Release build, clean with:

  xcodebuild clean -configuration Release  
  
* Build Audacity and create DMG and ZIP bundles in 
  /private/tmp by typing the following in the terminal:

  xcodebuild -configuration Release install   

* If you use the Xcode application, don't make any changes to 
  Audacity.xcodeproj recommended by Xcode. In particular, be sure to leave the
  Base SDK configuration set to 10.7 as it is now. 

If you need Audacity to show languages other than English, 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