build opencv for ios failed

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Hello, I am working on macos, I followed the instructions to build opencv for ios found here https://docs.opencv.org/2.4/doc/tutor... The build fails with the following error:

** BUILD FAILED **


The following build commands failed:
    Check dependencies
(1 failure)
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ERROR: Command '['xcodebuild', 'BITCODE_GENERATION_MODE=bitcode', 'IPHONEOS_DEPLOYMENT_TARGET=8.0', 'ARCHS=armv7', '-sdk', 'iphoneos', '-configuration', 'Release', '-parallelizeTargets', '-jobs', '4', '-target', 'ALL_BUILD', 'build']' returned non-zero exit status 65
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Traceback (most recent call last):
  File "opencv/platforms/ios/build_framework.py", line 137, in build
    self._build(outdir)
  File "opencv/platforms/ios/build_framework.py", line 123, in _build
    self.buildOne(t[0], t[1], mainBD, cmake_flags)
  File "opencv/platforms/ios/build_framework.py", line 256, in buildOne
    execute(buildcmd + ["-target", "ALL_BUILD", "build"], cwd = builddir + "/modules/objc/framework_build")
  File "opencv/platforms/ios/build_framework.py", line 40, in execute
    retcode = check_call(cmd, cwd = cwd)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 190, in check_call
    raise CalledProcessError(retcode, cmd)
CalledProcessError: Command '['xcodebuild', 'BITCODE_GENERATION_MODE=bitcode', 'IPHONEOS_DEPLOYMENT_TARGET=8.0', 'ARCHS=armv7', '-sdk', 'iphoneos', '-configuration', 'Release', '-parallelizeTargets', '-jobs', '4', '-target', 'ALL_BUILD', 'build']' returned non-zero exit status 65

If I give that xcodebuild command manually from terminal with the arguments above, it does complain the syntax is wrong. I somehow doubt the syntax error is just a bug in the installer or there would be a lot more complaints, so I assume something's wrong on my side, but I can't think what. Any ideas? Thank you.