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

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?

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

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

@vj9 thx. I update to xcode 7 . It show me the same error. Build well after set "NO"

set "NO" it works well.

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.

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.