As suggested here I've been able to import my existing Objective-C code into a .swift file via the bridging header. As of yet I've been unable to do something similar with a swift playground - it does not seem to recognise the header in the same way that a swift file does.
Interestingly, and possibly suggestive of a negative to my question is that playgrounds do not appear to share the concept of target membership like .swift/.m
Anyone had any success with this or perhaps a different mechanism?