Click here to download the Disk Image of iOS 11
Go to Application and find Xcode 8, right click on it and click on show package content.
Go to Contents - > Developer - > Platforms - > iPhoneOs.Platform -> Device Support .
Paste that folder which is downloaded and restart your Device,Xcode and Mac OS.
Then you can run apps on iOS 11 using Xcode 8.2
Is it possible to build an app on iOS 10.3 devices with Xcode 8.2.1 without updating ?
How do you perform wireless debugging in Xcode 9 and iOS11 ?