It would be safer to run this as a pre-build script so the files are copied locally before the build begins to reduce any problems with network connectivity fluctuating mid-build or a race between targets in a parallel build. You can automate this in Xcode by using a feature of the scheme called a build pre-action. When you go to edit your scheme, open the disclosure triangle on the Build action, and you'll see 3 options, Pre-actions, Build, and Post-actions. You can add a shell script to the pre-action that does the copy.
Topic:
Developer Tools & Services
SubTopic:
Xcode
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