cross-compile Bitcoin-qt for MacOSX on Ubuntu

System: ubuntu 18.04
Bitcoin model: 0.21

I efficiently compiled the Ubuntu-qt, and Home windows-qt utilizing the Relies upon system. Nevertheless, I’m having a tough time doing the identical for MacOSX utilizing Ubuntu System.

I’ve downloaded the SDK from right here :

https://developer.apple.com/devcenter/obtain.motion?path=/Developer_Tools/Xcode_7.3.1/Xcode_7.3.1.dmg

Extracted it utilizing the script in contrib folder, then created a listing /relies upon/SDKs and place the extracted SDK in there.

After that, I run:

make HOST=x86_64-apple-darwin18 SDK_PATH=<some-path>/relies upon/SDKs/MacOSX10.11.sdk/

However everytime I find yourself with identical error:

./increase/config/posix_features.hpp:18:15: deadly error: 'unistd.h' file not discovered
funcs.mk:242: recipe for goal 'path/relies upon/work/construct/x86_64-apple-darwin18/increase/1_64_0-57fba19f366/./.stamp_built' failed

Are you able to somebody assist ?