If you have XCode installed you can go to preferences, downloads, and install the iOS Simulator, at this time the
iOS 5.0 Simulator is the only one available, even though
iOS 6.0 is already out.
Once it’s installed you’ll have a new application – but it is not clear where the application is actually stored.
You’ll need the path for the
iOS Simulator if you want to actually launch it or open it.
Fortunately that’s not a big problem – the iPhoneSimulator can be found at: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Applications/iPhone Simulator.app
Now all you have to do is open it. Voila!