Feature Request: Add MacOS Support

[ShammyLevva]

Could the iOS code be adapted with minimal effort to provide MacOS In App Purchase support?

[jamesmontemagno]

I will not be implementing it as I have no plans here, however anyone can send a PR.

[tussock]

It seems that the only reason that the InAppBilling.apple.cs uses UIKit is to perform:
static bool IsiOS112 => UIDevice.CurrentDevice.CheckSystemVersion(11, 2);
i.e. to see if the version is 11.2 or later.

This is used later for introductory prices.

LocalizedIntroductoryPrice = IsiOS112 ? (p.IntroductoryPrice?.LocalizedPrice() ?? string.Empty) : string.Empty, 
MicrosIntroductoryPrice = IsiOS112 ? (long)((p.IntroductoryPrice?.Price?.DoubleValue ?? 0) * 1000000d) : 0

Otherwise, it looks like this code should be portable between mac and iOS.

Cheers.

[Suplanus]

@tussock
I had a look into it... there are problems with SkPayment and SkPaymentTransaction:

Have no idea how to handle the tokens.

[jamesmontemagno]

#354

Will be in 4.1.0 there will not be a transaction receipt though as you will need to call the native APIs for it