After upgrading Xcode to version 11, I found that some of the simulators that I commonly use were missing. I used the following steps to restore them.
- In Xcode the Window menu, select "Devices & Simulators"
- Make sure the Simulators tab is selected
- Use the "+" in the bottom left to add simulators that are missing
- A modal will pop up with "Create a new simulator"
- Use the second drop down to select the device type
- The rest of it can be left as default or you can give it a unique name and select the OS version
- Click "Create"