A solution to “Symbol not found: _objc_readClassPair”

I’m using [Greenhouse CI](greenhouseci.com), they’ve got test machines running under OS X Mavericks. My iOS project was failing during attempt to run tests. Some googling brought to me several similar OS X issues mentioning 10.10 test deployment target being a culprit, and this issue gets fixed by setting target to 10.9

It appeared that the same solution applies to iOS projects - you need to set OS X Deployment Target to 10.9 for your iOS tests, and everything starts to work.