Starting February 1, 2015, new iOS apps uploaded to the App Store must include 64-bit support and be built with the iOS 8 SDK, included in Xcode 6 or later. To enable 64-bit in your project, we recommend using the default Xcode build setting of Standard architectures to build a single binary with both 32-bit and 64-bit code.
While requiring the iOS 8 SDK is similar to what Apple requested last year with the iOS 7 SDK, the 64-bit support request is substantial.
Apple introduced 64-bit processors in 2013 with the A7 that powered the iPhone 5s, iPad Air, and iPad mini with Retina display.
Currently, Apple only sells a few low-end devices without 64-bit support, so it seems to be a good time to require developers support the new technology.