Hi robink1
I have question : Which iOS is currently in your iPhone 6 ?
Currently latest Xcode version is 10.0. You can check for Xcode update from the App Store and update, but as you said, you can't find update in the App Store. So I guess you didn't login with Apple ID in the store.
After that if you will not find update of Xcode, then you can manuaaly aownload and install from here :
https://developer.apple.com/download/
Or you can Clean, Build and Archive, then export .ipa and directly install it :
- Select Generic iOS Device after Active Scheme at top left corner of Xcode
- Clean, Build and Archive project
- Export build from the Organizer
- Select Window from top menu --> Device and Simulators
- Select your attached iOS device (iPhone 6)
- Drag and drop exported .ipa and wait untill app list is refreshed.
Thanks.