How to compile OpenCV iOS with ENABLE_BITCODE

Question

When I tried to compile my XCode project with OpenCV 2.4 iOS using XCode 7 + iOS SDK 9, XCode complained that

ld: \'opencv2.framework/opencv2(alloc.

Answer 1

OpenCV is precisely the kind of software (along with audio and video Codecs) that is likely to have hand-rolled ARM NEON optimisations. The documentation suggests that ~40 functions have had this treatment in OpenCV3.0.

If compiling for LLVM bit-code you'll get the generic (less optimised, implemented in C or C++) versions instead.

Use of Bitcode is optional - except when compiling for Apple watch, where it's hard to imagine you'd run computationally complex image processing anyway. If you're bundling a watch app, override the build setting for bitcode on it only.