Sudden error "The iOS 8.4 simulator runtime is not available." in Xcode 6.4

Question

I'm not sure what happened. All of a sudden the simulator doesn't work, and I haven't done a single thing differently with XCode. The simulator has been operative for the past 2 weeks, and when I went to run my program again, I got the error "The iOS 8.4 simulator runtime is not available.". I didn't upgrade XCode, didn't change any settings, and I didn't even close XCode between simulations. It was literally out of nowhere. When I try to stop the simulation, the run/stop buttons don't work. Has this happened to anyone else??

EDIT: The error tells me "Download the iOS 8.4 simulator runtime from the Downloads section in Xcode's Preferences", but it doesn't exist in there.

Answer 1

Under Xcode > Preferences > Downloads > Component check if iOS 8.4 simulator is present. One of the possible solutions is to restart your MAC book, this bug might get fixed by doing so

Answer 2

Found the problem...XCode was listed as XCode 2 in my Applications folder and I changed it back to XCode (after closing it first). For some reason that screwed things up. I changed it back to XCode 2 and now it's working again. I guess I'll just have to live with that name :/

Answer 3

I had the same problem. The solution, that helped me is to specify Xcode version via xcode-select:

% sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/

After that you can check your available SDKs:

% xcodebuild -sdk -version