Xcode preparing to erase and reinstall my hard drive

Essentially this is the same as setting up a new Mac. You will need to import the certs that you had imported.

I use git from the command line to download my apps' source onto the new Mac. The certs are needed so you install your app on a iOS device. For Mac apps, the certs let you upload your app to the app store. Notarized apps need certs too.

From Xcode > Preferences... > Accounts

Select your Apple ID, then click the tiny cog at the bottom of the dialog.

• Import Apple ID and Code Signing Assets...

• Export Apple ID and Code Signing Assets...

Remember to also transfer your Source Control Accounts (and any associated ssh keys).

You may also want to backup any Themes customisation (stored in ~/Library/Developer/Xcode/UserData/FontAndColorThemes/), and make a note of any Behaviors.

What are source control accounts? and ssh keys?

What are source control accounts? and ssh keys?

If you don't know, you are probably not using them!
They appear in Xcode Settings > Accounts (under the Apple IDs section).

Source Control (e.g.):

• GitHub

• Bitbucket

ssh keys (in this context):

• Used to secure the connection to the source control account