IIRC the problem with GNUStep is that it got stuck at a version of Objective-C and Cocoa/AppKit roughly equivalent with that of OS X 10.6 and would take a lot o

IIRC the problem with GNUStep is that it got stuck at a version of Objective-C and Cocoa/AppKit roughly equivalent with that of OS X 10.6 and would take a lot of work to even catch up to modern Obj-C and Cocoa, let alone get Swift integrated into.