How do you update Xcode on OSX to the latest version?

1. Open up App Store

   

2. Look in the top right for the updates section (may also be in lefthand column "Updates"..)

   

3. Find Xcode & click Update

softwareupdate --list see the list of outdated software.

softwareupdate --install --all update all outdated software.

softwareupdate --install <product name> update the software you named.

Sometime I don't see the Xcode update in Updates tab in AppStore
So I search Xcode in AppStore

Then click update and it update

If attempting to download via the App Store leaves you with a little grey spinner and nothing actually happening, then you can go to :

https://developer.apple.com/download/more/

log in with your Apple Developer ID, and the latest Xcode should be available as a .zip download.