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iOS developers recently received an email from Apple stating that

Starting February 1st, new apps and app updates submitted to the App Store must be built with XCode 4 and iOS 7 SDK

The email included a link about building apps for iOS 7.

One of the item on this page, is about 64-bit compilation.

So the question is, should I deduce that 64-bit is now a REQUIREMENT, or is it still a recommendation?

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Nope, definitely not a requirement. It is entirely possible to just build for ARMv7, as the instruction set is backwards compatible. Eventually, ARMv7 will be phased out like ARMv6 was, but until all devices are running the ARM64 instruction set, they must allow apps that don't have 64 bit enabled. –  Richard J. Ross III Jan 14 at 9:04
    
XCode with the iOS 7 SDK builds both binaries for you and combines them. –  Andrew Larsson Jan 16 at 23:10

2 Answers 2

up vote 3 down vote accepted

64-bit is a recommendation. Since not all devices run 64-bit, they must allow 32-bit apps on the App Store. Only when all devices run 64-bit can Apple enforce such a restriction, otherwise all new apps wouldn't work on older devices.

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iOS apps use universal binary. That means one app can contain both of 32-bit and 64-bit code.

  • If your device supports 64-bit mode, then your app will be run in 64-bit mode which is a lot faster.
  • If your device supports only 32-bit mode, then 32-bit code will be run.
  • 64-bit Apple processors all have 32-bit compatibility mode, so legacy apps (32-bit only) will just work.

Actually in 32-bit mode, there're two different 32-bit architectures, and Apple is dealing with them very smoothly. Most people don't even know there's different 32-bit modes.

If you're a user, you have nothing to care, and everything will just work. If you're a developer, you code will just work unless you are using some unrecommended hacks.

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