Trying to run xcode on an unsupported OS is asking for trouble. Use Parallels to run the old OS.
On macOS 10.12 Sierra, I can build my plug-ins for InDesign CC 2017.x using XCode 8.x.
On OS X 10.11 El Capitan, I can build my plug-ins for InDesign CC 2015.x using Xcode 6.4, and for InDesign CC 2017.x using XCode 7.2.1.
On OS X 10.10 Yosemite, I can build my plug-ins for InDesign CC - CC 2015.x using Xcode 5.0.2, and for InDesign CC 2017.x using XCode 7.2.1.
I'm using Xcode 5.0.2 and Xcode 8.2.1 on OS X 10.11.
Xcode 5.0.2 is used for InDesign CC 2014/5 plug-in building. Command line works well. To run Xcode 5.0.2 UI, use command
/Applications/Xcode5.app/Contents/MacOS/Xcode </dev/null &>/dev/null &
My plugin compiles on OS 10.11 with xcode 7.1. But when I switch to OS 10.12 with xcode 8.1 (on separate machine), I get a link error:
clang: error: no such file or directory: '/Users/apple/SDKs/CS12.1SDK/build/mac/prj/build/x-changer.build/Default/Release_Cocoa64. build/Objects-normal/x86_64/x-changer.CC17.v1.1_lto.o'
Can you advise what is needed to compile/build on Xcode 8.1 ? It seems you have solved the issue.
Thanks in advance.
My advice is to install and use the version of XCode which the SDK was created for. It MIGHT be possible to adapt, but you are making needless problems for yourself. If this does not run in your OS, use Parallels to do so.
Yes I am using Xcode 8.2.1 on macOS Sierra to build plug-ins for InDesign CC 2017.
Copy MacOSX10.11.sdk from Xcode 7.x to Xcode 8.x.
It is placed at Xcode/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs folder.