This is a useful tip if you have to do any type of mobile web testing for iOS Safari and you either don’t have an iPhone/iPod Touch or you don’t feel like plugging it in and setting things up. As long as you have Xcode installed, you can simply open a terminal and run the following command:
MACBOOK:~ user$ open -a iPhone\ Simulator
This should launch the last simulator you had running. If you need to run a different version of iOS or switch to a different device profile, you can do that once the simulator has started. Hopefully this works for you – you can even create a shortcut and put it on your desktop or in the dock if you find yourself running this command often.