I have followed all the instruction mentioned at Creating Your First Safari Extension App. After running FirstSafariExtensionApp target, I have opened Safari preferences Extensions tab but I couldn't find My Extension in the left pane. I have Apple Developer membership and installed Mac Developer and Safari Extension Developer certificates in the KeyChain.
How to get my first safari extension app working?
I had the same problem, the Extension didn't show when running the app even though I made sure to allow unsigned extensions.
I could run the extension target by choosing Safari as app to run but that's not what I wanted.
It was only after I hit Product > Clean Build Folder that the extension would show up when running the app.
Did you enable the Develop menu in Safari and turn on the “Allow Unsigned Extensions” option?
That did not work for me, so I tried running the scheme for the extension rather than the scheme for the app. I first edited this scheme to set the executable to the containing app.
When I ran this, the extension showed up in the Safari preferences, but only while the app was running.
Close your MacBook lid and goto sleep. Wake up in the morning and check Safari preferences extensions tab; You will find the extensions you are looking for. If you don't have time to sleep, try restarting the Safari or Xcode or Mac.
Restart your Safari browser and it will be shown up in the Extensions tab.
Gary Makin is right, I think Apple's doc is out of date.
- You need to run the scheme for extension instead
- Choose Safari when it shows "Choose an app to run"
- After safari launched, you should be able to find "My Extension" in extension tab
For every change in your extension code, you have to stop it, rebuild and run agian, it will restart Safari for you
来源：https://stackoverflow.com/questions/46306016/safari-extension-app-is-not-shown-in-safari-preferences-extensions-tab