iOS 8

Apple has sent out word to their third-party app developers that any updates to their existing iOS apps must be made with the iOS 8 SDK and offer 64-bit support by June 1, 2015.

This news comes just a few months after Apple announced that any new iOS 8 apps submitted to iTunes for publication must be 64-bit compatible by February 1. This new development means that all of the iOS 8 apps in iTunes will take full advantage of the 64-bit support in Apple's A7 and A8 chips by June 1.

Source: 9to5Mac