The clarification from Apple comes after developers expressed confusion regarding the company's 64-bit app update policies. With Wednesday's announcement, developers now have more than six months to prepare for the switch.
All newly submitted apps will require 64-bit support beginning on Feb. 1, 2015. They must also be built with the iOS 8 software development kit as of that deadline.
But developers will have longer to prepare their existing applications, as app updates will be allowed to remain 32-bit-only through the end of May.
Apple has advised developers that they can enable 64-bit in their project by using the default Xcode build setting of "Standard architectures." This will build a single binary with both 32- and 64-bit code.
Apple began alerting developers to the 64-bit requirement for new applications in October, which caused confusion about existing app updates. Apple was first to bring 64-bit portable computing to the mainstream with the launch of the iPhone 5s in 2013.