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I've heard a lot of talk that enabling bitcode decreases the binary size of an app downloaded from the app store onto iOS 9. I haven't been able to find any resources on whether or not bitcode decreases the binary size on previous iOS versions.

Does enabling bitcode decrease the binary size on iOS 7 or iOS 8?

EDIT According to this thread App Slicing and Bitcode are two separate components. This would make sense considering the documentation for App Thinning splits them into different sections. Is there any official word from Apple on iOS requirements for Bitcode?

Awesome-o
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  • "I've heard a lot of talk that enabling bitcode decreases the binary size of an app downloaded from the app store onto iOS 9" *Official* "talk" from Apple, or unofficial talk by other people? – user102008 Jan 12 '16 at 01:24
  • Mostly unofficial, the documentation clearly states that this is a part of "App Thinning" and that it exists to re-optimize apps compiled from the store but does not go into much detail. I think this has lead to a lot of confusion about bitcode's requirements which is why I bring this question up. Your question also revealed to me that I was making the assumption that bitcode would distribute the binary only necessary for that architecture, however that's not explicitly stated either - it may optimize/distro for all architectures. Again, back to the documentation leading to a lot of confusion. – Awesome-o Jan 12 '16 at 19:17

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No. App Slicing/Bitcode is for iOS 9 only. Devices with iOS-Versions older than 9.0.2 will automatically download the full sized bundle.

Source: http://www.macrumors.com/2015/10/05/ios-9-app-slicing-now-available/

FelixSFD
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I see that thread:

Another potential issue (can’t confirm it) - Bitcode thingie works only for iOS 9, so if you submit your app to the AppStore and it includes Bitcode, then malefactor can get the whole IR from your app using iOS 7/8 and jailbroken device.

From bitcode-demystified

Or another article: Bitcode

Another from SO: Bitcode

May it will helpful for you.

Community
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vien vu
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  • Those were some solid reads, thanks. In the comments it states "Do you really think that iOS 8 and lower will get the whole binary including the IR? I'd assume that Apple compiles a normal fat binary and strips the IR from it. Otherwise Apps would be getting bigger than before on devices without iOS 9." Reply "I guess they will just strip bitcode without recompiling, otherwise, as you said, it won't make any sense." The verdict is still out it seems. – Awesome-o Jan 10 '16 at 04:25