Updating Xcode on releasing new iOS version : A question always in my mind ,Why its important do download the news version of Xcode while any new ios version release .
Suppose I installed ios 11 in my mobile and i start developing an app with xcode8.3 version (which not support new version of ios i.e 11)

and then i have to download new version of OSX to 


Should this is not revert work with Apple .