Running multiple iOS Simulator instances is very helpful for testing purposes. This is helpful in testing same application on different devices simultaneously or with different user credentials simultaneously.
The default behaviour does not allow to run more than one simulator instance from XCode. But it is possible to do it from the command line.
For this change the directory into
Developer/Applications in XCode.app package and run simulator with the "open" command.
cd /Applications/Xcode.app/Contents/Developer/Applications open -n Simulator.app open -n Simulator.app
When the second simulator instance launches you’ll get an error message saying “Unable to boot device in the current state: Booted”. Dismiss the error message and proceed with the test.
Device hardware type can be changed from "Hardware >> Device" menu of the iOS Simulator.