On the latest episode of The Talk Show, The iPhone 5 Episode, John Gruber and MG Siegler discussed barcodes on an iPhone screen not scanning properly, and speculated that Passbook (a new feature of iOS 6) might require a special type of scanner. They’re partially right, as explained in the wwdc videos about Passbook1.
Passbook authors can choose between three styles of barcode:
Those three styles all have something in common: they’re 2D barcodes, as contrasted from the old-school 1D barcodes, as seen in most stores.2 The presenter in the WWDC videos explains their choice to only support 2D barcode formats.
Scanners for 1D barcodes typically use lasers to read them, and those do not work (at least not well) with iPhone screens, as I’ve experienced in the past with scanned-in rewards cards. The 2D formats can only be read by optical scanners (taking photos of the target), which work fine with iPhone screens. Passbook cranks up the brightness on the phone’s screen all the way when it’s displaying a barcode to make a successful scan even more likely.
Not all barcode scanners will properly read an iPhone’s screen, but Apple chose barcode formats for Passbook which require scanners that will work.
The links require an Apple Developer account, but not a paid one. The free accounts have access to the WWDC session videos. I think (and hope) these are no longer under NDA, since iOS 6 has been publicly released. ↩