A simple Playground demonstration on how to 

a) load an Apple IIGS 320x200 graphic file with a file type and auxiliary type of $C1 and $0000,

b) extract data from the loaded file and use the information to instantiate a raw bitmap which can be used by macOS to create a CGImage object,

c) create an instance of NSImage from the CGImage object, and,

d) display the NSImage object in a Playground view.

Requirements:

Written in Swift 3.x later
Xcode 8.x or later