Impact of Xcode build options Enable bitcode Yes No

Question

Yesterday I recognized a ton of warnings regarding the parse com library       URGENT  all bitcode will be dropped because   path  Parse framework Parse PFAnalytics o   was built without bitcode  You must rebuild it with bitcode enabled  Xcode setting ENABLE BITCODE   obtain an updated library from the vendor  or disable bitcode for this target  Note  This will be an error in the future    I am aware of the fact that I can remove those warning with this answer but am now wondering if it will have any negative impact in regards to AppStore submission and   or actual performance of my app   Xcode informs you regarding bitcode     Activating this setting indicates that the target or project should generate bitcode during compilation for platforms and architectures which support it   For Archive builds  bitcode will be generated in the linked binary for submission to the app store   For other builds  the compiler and linker will check whether the code complies with the requirements for bitcode generation  but will not generate actual bitcode   ENABLE BITCODE    But I am not getting any really useful information out of this text    Can I use the linked answer to circumvent the issue without any negative impact and without compromising a future AppStore submission   What does the ENABLE BITCODE actually do  will it be a non-optional requirement in the future  Are there any performance impacts if I enable   disable it

User · Answer

From the docs

can I use the above method without any negative impact and without compromising a future appstore submission?

Bitcode will allow apple to optimise the app without you having to submit another build. But, you can only enable this feature if all frameworks and apps in the app bundle have this feature enabled. Having it helps, but not having it should not have any negative impact.

What does the ENABLE_BITCODE actually do, will it be a non-optional requirement in the future?

For iOS apps, bitcode is the default, but optional. If you provide bitcode, all apps and frameworks in the app bundle need to include bitcode. For watchOS apps, bitcode is required.

Are there any performance impacts if I enable / disable it?

The App Store and operating system optimize the installation of iOS and watchOS apps by tailoring app delivery to the capabilities of the user’s particular device, with minimal footprint. This optimization, called app thinning, lets you create apps that use the most device features, occupy minimum disk space, and accommodate future updates that can be applied by Apple. Faster downloads and more space for other apps and content provides a better user experience.

There should not be any performance impacts.

User · Answer

What does the ENABLE BITCODE actually do  will it be a non-optional requirement in the future       I m not sure at what level you are looking for an answer at  so let s take a little trip  Some of this you may already know   When you build your project  Xcode invokes clang for Objective-C targets and swift swiftc for Swift targets  Both of these compilers compile the app to an intermediate representation  IR   one of these IRs is bitcode  From this IR  a program called LLVM takes over and creates the binaries needed for x86 32 and 64 bit modes  for the simulator  and arm6 arm7 arm7s arm64  for the device   Normally  all of these different binaries are lumped together in a single file called a fat binary   The ENABLE BITCODE option cuts out this final step  It creates a version of the app with an IR bitcode binary  This has a number of nice features  but one giant drawback  it can t run anywhere  In order to get an app with a bitcode binary to run  the bitcode needs to be recompiled  maybe assembled or transcoded    I m not sure of the correct verb  into an x86 or ARM binary   When a bitcode app is submitted to the App Store  Apple will do this final step and create the finished binaries   Right now  bitcode apps are optional  but history has shown Apple turns optional things into requirements  like 64 bit support   This usually takes a few years  so third party developers  like Parse  have time to update         can I use the above method without any negative impact and without compromising a future appstore submission       Yes  you can turn off ENABLE BITCODE and everything will work just like before  Until Apple makes bitcode apps a requirement for the App Store  you will be fine         Are there any performance impacts if I enable   disable it       There will never be negative performance impacts for enabling it  but internal distribution of an app for testing may get more complicated   As for positive impacts    well that s complicated   For distribution in the App Store  Apple will create separate versions of your app for each machine architecture  arm6 arm7 arm7s arm64  instead of one app with a fat binary  This means the app installed on iOS devices will be smaller   In addition  when bitcode is recompiled  maybe assembled or transcoded    again  I m not sure of the correct verb   it is optimized  LLVM is always working on creating new a better optimizations  In theory  the App Store could recreate the separate version of the app in the App Store with each new release of LLVM  so your app could be re-optimized with the latest LLVM technology

User · Answer

Make sure to select  All  to find the enable bitcode build settings

User · Answer

vj9 thx  I update to xcode 7   It show me the same error  Build well after set  NO     set  NO  it works well

User · Answer

Bitcode makes crash reporting harder  Here is a quote from HockeyApp  which also true for any other crash reporting solutions       When uploading an app to the App Store and leaving the  Bitcode  checkbox enabled  Apple will use that Bitcode build and re-compile it on their end before distributing it to devices  This will result in the binary getting a new UUID and there is an option to download a corresponding dSYM through Xcode    Note  the answer was edited on Jan 2016 to reflect most recent changes

User · Answer

Bitcode is a new feature of iOS 9  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  Note  For iOS apps  bitcode is the default  but optional  If you provide bitcode  all apps and frameworks in the app bundle need to include bitcode  For watchOS apps  bitcode is required  So you should disabled bitcode until all the frameworks of your app have bitcode enabled

[ios] Impact of Xcode build options "Enable bitcode" Yes/No

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