Can't get a Source Editor extension working in Xcode 10

Question

Using Xcode 10 running in Mojave I can't get a simple test source editor extension working. I use to be able to do it under Xcode 9 High Sierra. I created a bare bones source editor extension. I then run it but doesn't show up under the debut Xcode (black icon) Editor menu. Also doesn't show up in System>Extension list. Rebooting didn't help either. I tried downloading LineX extension from the Mac App Store but it wouldn't work either.

Answer 1

It's now fixed but I have no idea how. After working on it for four days I about gave up. I wanted to retry LineX extension but I first searched my drive for all files containing LineX and deleted them Except for the one in the Applications folder. I restarted the Mac and went to bed. Next morning its was working. LineX and two other extensions plus my extension showed up in System>Extensions and now are working. I hate when something starts working but you don't know why but I guess it's better than not working.

Answer 2

My Xcode Source Editor extensions have, on more than one occasion, disappeared from Xcode. Each time they have disappeared, I always eventually got them to reappear––until Xcode 12. With Xcode 12 I was unable get any Source Editor extensions to show up in System Preferences/Extensions, until today.

I just found the answer to why Xcode Source Editor extensions keep disappearing: It has to do with my maintaining older versions of Xcode on my my MacOS Catalina system. I keep Xcode versions 10, 11, and 12 on my development system, and according to this thread that I found: https://github.com/nicklockwood/SwiftFormat/issues/494

The thread quotes from The article Xcode​Kit and Xcode Source Editor Extensions by Zoë Smith, March 25th, 2019, says:

Finally, when multiple copies of Xcode are on the same machine, extensions can stop working completely. In this case, Apple Developer Relations suggests re-registering your main copy of Xcode with Launch Services (it’s easiest to temporarily add lsregister’s location to PATH first):

% PATH=/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support:"$PATH"
% lsregister -f /Applications/Xcode.app

After issuing these terminal commands my Source Editor Extensions are now, once again, available!

Answer 3

Renaming or moving the Xcode will fix the issue. Since High Sierra since /usr/libexec/xpccachectl (the preferred solution) does not seem to exist in this version of the OS.

To fix quickly:

• Quit Xcode
• Rename Xcode in the applications folder temporarily.
• Launch renamed Xcode
• Quit Xcode
• Name it back to old value

Answer 4

Possible solution for High Sierra 10.13.6: install "Security Update Developer Beta 10.13.6" (2018-002)" from Mac App Store. I've got "Xcode Source Editor" in the Extensions prefpane back right after post-update reboot.

Answer 5

Faced a similar issue when was trying to run Xcode Source Editor extension (Xcode 11.2.1). As a result - my extension didn't appear in "Editor" menu.

Here's a list of all my actions (after following them the problem has gone):

Make sure that signing for both host app and extension is set to "Automatic" and Signing Certificate is set to "Development" (or any other except "To Run Locally").

Then:

1. Go to Xcode settings, select "Accounts" tab, select your Apple ID account (add it if you don't have yet)
2. In "Teams" table select your team (you should have at least one - Personal Team)
3. Click "Download Manual Profiles"
4. Click "Manage Certificates...", then click a "+" button and choose "Apple Development"

Xcode might ask you a password for your development keychain (NOT your system one) - leave password field empty and press Return.

Hope this helps, good luck!