Just a workaround until something permanent. Two things: (1) don't use automatic preview - if you can make due with the Simulator, and (2) keep the activity monitor up so when swift-frontend shows its ugly head you can quit it... don't force quit, and don't quit xcode. Good luck.

What works for me as a workaround, just two things: (1) don't use automatic preview - if you can make due with the Simulator, and (2) keep the activity monitor up so when swift-frontend shows its ugly head you can quit it... don't force quit, and don't quit xcode. Good luck.