The only advice I can give is to follow the reply in that thread:
You'll need some ObjC/Swift code to handle the resource download and management.
Then once you know the resource is loaded you can use the
imageNamed: method to access the image file (and its data). I'd try the code given in that reply first. If that doesn't work you'll have to write some platform code to access the image data. If you want to use other formats beyond PNG you'll have to again figure out the best way to open it. My guess would be you could use NSData and then pipe that into the
Texture::initWithData c++ method.
You'll also need to know how to handle writing platform code. With ObjC you can essentially just have a mixed .mm file, whereas with Swift you'll probably need to have a bridging ObjC file to interface. I'd use ObjC for now. Check the source for the various platform code /platform/apple/ to check how this is handled if you're not sure.
Sorry, that's the best help since I've yet to use the platform-specific file hosting or slicing features since they increased to 100MB on iOS/Android/tvOS and on desktop Steam/Humber/itch.io/AppStore allow larger installs.