Cracking the Code Behind Apple’s App Store Promo Card Design
Apple’s App Store gift cards have a special trick: you can simply hold one up to your iPhone or Mac’s camera and it’ll automatically scan in the code and redeem the card for you. As developers, we thought it’d be cool to print some of our own promo code cards to give away at events, so we tried to create our own scannable cards.
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The app seems to recognize two things: A surrounding box and a code in the middle of this box. Once the app recognizes this pattern, it draws an on-screen box and tries to identify the code inside the box. The box itself isn’t enough: the app only kicks off its code recognition engine as soon as it finds specific characteristics of the specific font.
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This private framework is what iTunes and the App Store on your iPhone use to recognize codes. As it turns out, that’s where the elusive font is stored. There are two fonts:
- ‘Scancardium’ is used for entering and recognizing codes.
- ‘Spendcardium’ looks as though it’s used to obscure sensitive credit card details as you enter them.
