I know as for Appium Mobile Automation you need .app file to run ios app on Simulator.So as like me many of you face this problem. So I explain how to create that .app file and where it is located.
1.Open Xcode.
2.Click on your sample project.(If you don't have then click on create new xcode project)
3.In left panel inside screen you will see products folder then click and expand that, you will see the list.