Multiple iOS Simulator Support in Xcode 9
Xcode 9 was announced at WWDC17 earlier this year. I think it is probably one of the best Xcode releases to date, with a plethora of new features including a markdown editor which I am using for writing this post and considerably less buggy than it’s predecessors! One of the features that got me very excited was the ability to run multiple iOS simulators at the same time ! Finally …Now you can simulatneously test the app on different iOS versions and devices at the same time. The only limitation to the number of simulators you can run in parallel is the (memory/CPU) resources on your Mac. You would launch the app as usual by selecting the simulator as shown below 
If you want to run the app simulatneously on another simulator, you would go about that as shown below. 
That’s it!