Not just sitting back after using 64-bit processors in its newer devices, Apple is now pushing developers to make use of the advanced hardware. The company has issued a notice to developers stating that post 1st February, all new apps submitted in the App Store must come with 64-bit support and must be built using the iOS8 SDK. Also, post June 1st, updates to existing apps must also include the same change. Apple recommends that developers build apps using the default X code build setting “Standard architectures,” that allows to build a single binary with both 32-bit and 64-bit code.
Apple had already notified developers of the incoming change back in October so it shouldn’t come as a surprise for anybody. In terms of user experience, it isn’t likely to be a big change initially, but of course, the effects will start to show up gradually.
[Source]