By default, React Native projects target a minimum of iOS 7, but our projects were set to iOS 8 because previously we used a dynamic framework.
When building for an iOS 7 minimum target version, the linker would complain about thread local variables not working on iOS 7. So it was necessary to add even more checks (iOS >= 8 or OS X >= 10.7) before using native thread local variables rather than our shim.
This also changes our projects to target iOS 7 so we can catch these issues quicker in the future.
We needed to do this due to the way React Native modules work. Our hacky solution for using a framework ended up falling apart due to it relying on symbols not getting stripped from the main application.
This static library is in its own Xcode project because rnpm links in *all* static libraries from a given Xcode project.
This doesn't appear to have been necessary and seems to sometimes cause an issue because the packager will start and look for a JS file that was just deleted.
The target dependencies are discovered implicitly, and removing the use of explicitly defined dependencies actually resolved a very odd bug with Xcode when building ReactExample.app for a device.
Ari Lazier
Scott Kyle