Initial iOS Support and Example - #1631

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CLAs look good, thanks!

Jenkins, test this please.

@petewarden The failures still show bazel 0.2, are the new docker files not pushed out yet? Or did something go wrong with the bazel update? Or is this just a too old test?

@tensorflow-jenkins: test this please

This was a recent test, I need to debug what's going wrong on the Jenkins server. The install script does appear to be updated:
https://github.com/tensorflow/tensorflow/blob/master/tensorflow/tools/ci_build/install/install_bazel.sh

@tensorflow-jenkins: test this please

I just checked, and at least on the Mac, bazel 0.2.1 is definitely installed

You have the same error in linux build with 0.2.1 as well as on mac where is 0.2.0.

@martinwicke you have checked only mac0-slave, right?

@caisq can you upgrade bazel on mac1-slave, please?

Oh, right, I have only updated mac0-slave to 0.2.1.

I've installed the 0.2.1 binaries locally, and it seems like the fix we need didn't make it in, despite being in top-of-tree ahead of time! :( I'm following up with the Bazel team to find out what happened, and what we can do to fix this.

any updates on this patch?

We're currently blocked because the top-of-tree protobuf is broken, and we need that for iOS support. I'm working on fixing that right now.

I've been attempting to use this patch locally to see if I could manually work around the issues in protobuf. I've run into issues with Xcode 7 where object files built using the bazel cc_library rule can't be linked into an iOS simulator application due to metadata that's now being written into the object files. Going back to the bazel iOS example (http://bazel.io/docs/tutorial/ios-app.html) and adding some C++ code, I found that I was only able to get it to build properly if the C++ was added using an objc_library rule, not a cc_library rule.

I note that this patch currently only defines a cc_library rule for the tensorflow code. Does it also need to define an objc_library rule for the benefit of the simulator?

Edit: Explanation of Xcode 7's new object file metadata: https://karp.id.au/a/2015/09/15/xcode-7s-new-linker-rules/

@petewarden is this PR still active or can it be closed?