iOS simulator is not launching

I also have this issue and googled this, which redirect to this question. Mine was xcode10 What i have done is as follows

1. Quit the simulator & Xcode.
2. Opened Activity monitor, selected cpu option and search for sim, killing all the process shown as result.
3. Then fired up the terminal and run sudo xcrun simctl erase all. It will delete all content of all simulators. By content if you logged in somewhere password will be gone, all developer apps installed in that simulator will be gone.

Doing these resolved my issue.