For Xojo iOS projects, you can easily change the type of device that is being used by the simulator.
1. In the Navigator area, select iOS.
2. In the Inspector area, you'll see settings for "iOS Debugging." By default, the "Simulator Device" is set to "iPhone 4s (iOS8.1)."
3. Select another device (whether it be another iPhone or an iPad) from the menu.
From that point on, the selected device will be used when you run the app in the iOS simulator.