| Test | Command / Action | Expected Result | | :--- | :--- | :--- | | Xcode launches | Click Xcode.app | No crash, welcome screen appears | | Compiler works | swift --version | Swift version 4.2.1 | | CLI tools installed | xcrun --version | No "missing tools" error | | Simulator runs | Xcode → Open Developer Tool → Simulator | iOS 12 simulator boots | | Build a project | File → New → App | Build succeeds without SDK errors |

4. How to Install Only Command Line Tools (Alternative Method)

You'll need to log in with your Apple ID. — a free Apple ID works just fine for downloading Xcode.

Right-click (or Control-click) Xcode.app and select Open . Then click Open in the dialog. This bypasses Gatekeeper for the first launch.

Use a wired internet connection or a stable Wi-Fi. The download is large. If it fails, Safari’s download manager can resume partial downloads.

The definitive answer is that the last compatible version of Xcode for macOS High Sierra 10.13.6 is (with an update to 10.2.1 potentially possible via a workaround). This section will serve as your roadmap, clarifying which specific versions you can use and, most importantly, which ones you cannot.

If you are interested, I can also provide a guide on how to update your Mac to a newer OS if you find these limitations too restrictive.