'kAudioOutputUnitProperty_OSWorkgroup' is unavailable in Swift

When trying to access a kAudioOutputUnitProperty_OSWorkgroup the compiler errors by indicating:

'kAudioOutputUnitProperty_OSWorkgroup' is unavailable in Swift: Swift is not supported for use with audio realtime threads

This makes total sense! But I'm just fetching a property here... . I am not in real-time thread! In the world of Mix-N-Match (between C, ObjC++ and Swift) we should be able to fetch a property like this when we're not in a critical block.

Or am I missing something here?!