Failed to install "iOS 6.1 Simulator" XCode 5

Question

I want to run my app on both simulators ios6 and ios7. I'm trying to install ios 6 simulator but I am getting this error:

Failed to install "iOS 6.1 Simulator" An unknown error occured. Please try again later. 

I restarted XCode but not working stil..

Answer 1

Try to reset iOS 6.1 simulator from menu "iOS Simulator -> Reset Content and Settings...",

then run your app in XCode. This helped me.