What does ENABLE_BITCODE do in xcode 7?

ios iphone xcode7 bitcode
damithH picture damithH · Jun 9, 2015 · Viewed 122.7k times · Source

I have a problem with the embedded bitcode term.
What is embedded bitcode?
When to enable, ENABLE_BITCODE in new Xcode?
What happens to the binary when enabled, ENABLE_BITCODE in Xcode 7?

Answer

keji picture keji · Jun 9, 2015

Bitcode refers to to the type of code: "LLVM Bitcode" that is sent to iTunes Connect. This allows Apple to use certain calculations to re-optimize apps further (e.g: possibly downsize executable sizes). If Apple needs to alter your executable then they can do this without a new build being uploaded.

This differs from: Slicing which is the process of Apple optimizing your app for a user's device based on the device's resolution and architecture. Slicing does not require Bitcode. (Ex: only including @2x images on a 5s)

App Thinning is the combination of slicing, bitcode, and on-demand resources

Bitcode is an intermediate representation of a compiled program. Apps you upload to iTunes Connect that contain bitcode will be compiled and linked on the App Store. Including bitcode will allow Apple to re-optimize your app binary in the future without the need to submit a new version of your app to the store.

Apple Documentation on App Thinning

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