Its a chain...of memories.
Basically, GBA4iOS 2.0 allows any iPhone or iPad user to play Game Boy and Game Boy Advance games. We create controller skins that enable you to play the games on the screen. I use a template to feature amazing work of art like this one so people can download.
You can see some examples of them here: gbaskin.com
And you can see and download them here: gba4ioskins.com