Simulator helps you find major problems in your app during design and early testing. For example, the Debug menu in Simulator offers tools that help you:
Slow an animation to spot any problems
Change the graphics quality
Trigger iCloud sync
Identify blended view layers that harm app performance
Identify images whose source pixels aren’t aligned to the destination pixels
See what content is rendered offscreen
Simulate different locations
In every simulated environment in Simulator, the Home screen provides access to apps—such as Settings, Contacts, Maps, and Passbook—that are included with an iOS or watchOS device. You can perform preliminary testing of your app’s interaction with these apps in Simulator. For example, if you are testing a game, use Simulator to test that the game uses Game Center correctly.
The Accessibility inspector in Simulator helps you test the usability of your app regardless of a person’s limitations or disabilities by displaying information about each accessible element in your app. The inspector also enables you to simulate VoiceOver interaction with those elements. To start the Accessibility inspector, click the Home button in Simulator. Click Settings and go to General > Accessibility. Slide the Accessibility Inspector switch to On.
You can test your app’s localizations in Simulator by changing the language. In Settings, go to General > International > Language.
Although you can test your app’s basic behavior in Simulator, the simulator is limited as a test platform for multiple reasons. For example:
Because Simulator is an app running on a Mac, Simulator has access to the computer’s memory, which is much greater than the memory found on a device.
Simulator runs on the Mac CPU rather than the processor of an iOS or watch OS device.
Simulator doesn’t run all threads that run on devices.
Simulator can’t simulate hardware features like the accelerometer, gyroscope, camera, or proximity sensor.
While developing your app, run and test it on all of the devices and OS versions that you intend to support.
For more detailed information, see Testing and Debugging in Simulator.