I tend to write apps that work on OSs from Snow Leopard to El Capitan, though the former has a 3D dock and the latter a flat design one. I've tried to draw icons that display ok on both, but 'ok' is about as far as it goes. Pixelmator's old icon displayed ok on Yosemite yet they still updated it to make it more flat.
Is there a way to make OS-specific icons? Should one make separate apps for that?
In Apple's human interface guidelines there is no mention of this problem, they only talk about one app icon. I've thought about their Dock Tile documentation which would allow one to change the icon at runtime, still not the perfect solution as the app would have to be executed once, to check for the OS, then change the icon if necessary.
