I am trying to compile this on 10.13, which with a couple modifications to the makefile seems possible. These errors I think I've worked around:

• NSApplication.shared() seems to not be supported anymore? I was getting this error, but removing this line of code doesn't seem to break anything yet.

minimal.swift:7:29: error: cannot call value of non-function type 'NSApplication'
        NSApplication.shared()
        ~~~~~~~~~~~~~~~~~~~~^~

• 'NSTitledWindowMask' is unavailable in Swift. Replaced this with .fullSizeContentView and it seems to have fixed it. Here's the error I was getting:

minimal.swift:10:42: error: 'NSTitledWindowMask' is unavailable in Swift
                              styleMask: NSTitledWindowMask,
                                         ^~~~~~~~~~~~~~~~~~
AppKit.NSTitledWindowMask:3:12: note: 'NSTitledWindowMask' has been explicitly marked unavailable here

I can't seem to get past this part:

minimal.m:6:13: warning: class method '+CreateWindow' not found (return type defaults to 'id') [-Wobjc-method-access]
    [Window CreateWindow];

Running minimal.go exhibits the same issue before crashing:

2018-07-26 16:59:58.242 minimal[22059:5510792] +[minimal.Window CreateWindow]: unrecognized selector sent to class 0x40d81a8
2018-07-26 16:59:58.243 minimal[22059:5510792] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[minimal.Window CreateWindow]: unrecognized selector sent to class 0x40d81a8'
*** First throw call stack:
(
	0   CoreFoundation                      0x00007fff3de372db __exceptionPreprocess + 171
	1   libobjc.A.dylib                     0x00007fff64fd8c76 objc_exception_throw + 48
	2   CoreFoundation                      0x00007fff3decfcf4 +[NSObject(NSObject) doesNotRecognizeSelector:] + 132
	3   CoreFoundation                      0x00007fff3ddad820 ___forwarding___ + 1456
	4   CoreFoundation                      0x00007fff3ddad1e8 _CF_forwarding_prep_0 + 120
	5   minimal.a                           0x00000000040d777e CreateWindow + 30
	6   minimal                             0x0000000004046700 runtime.asmcgocall + 112
)
libc++abi.dylib: terminating with uncaught exception of type NSException
SIGABRT: abort
PC=0x7fff65d42b66 m=0 sigcode=0

Is there something simple that I'm missing? I did some Objective C programming ages ago and have dabbled with Swift, but it's been quite some time.

With the help of this project I was able to create the library(minimal.a). I utilised this library for accessing swift code through go. I am accessing swift code through my go executable using this library. It is all working fine on my machine.
However, I get following error when I try to execute it on other machines.
dyld: Symbol not found: _$sBOWV
Referenced from: minimal.a
Expected in: /usr/lib/libswiftCore.dylib
in minimal.a
Abort trap: 6

I thought this is some kind of linking issue so I statically linked the library using following command
"xcrun swiftc minimalC.o minimalS.o -static-stdlib -emit-library -module-name minimal -o minimal.a". Using -static-stdlib the issue got resolved.

But, -static-stdlib is not supported on latest MacOS. So my question is how can I use this library on other machines without using -static-stdlib.

Note: Utilised this method to access swift from go but, underlying code is different

I tried to Google before asking here. However, Google found some questions without the answer, like this and this.

I tried to add a global function in minimal.swift; however, swiftc says

@objc can only be used with members of classes ...