To download and work with Xcode on macOS High Sierra 10.13.6, you must use Xcode 10.1
For macOS High Sierra 10.13.6, the latest compatible version of Xcode is Xcode 10.1. If you search for it on the App Store, you may only see the latest version (which won't work), so you typically need to download it directly from Apple's developer portal. How to Download Xcode 10.1 Go to the Apple Developer Downloads page. Log in with your Apple ID. Search for "Xcode 10.1" and download the .xip file. download xcode for mac os high sierra 10136 work
System Requirements:
shasum -a 256 ~/Downloads/Xcode_10.1.xip
, as it is the final version officially compatible with this OS. Apple Developer Quick Setup Guide Identify Your Version To download and work with Xcode on macOS High Sierra 10