I am having troubles when I connect with my repository through Xcode.
I have a Gitlab version (full pre-)installed on TurnkeyLinux Virtual Appliance on a remote server.
you'd better use the project configuration:
‘Source Control’ > ’(project name)-Master’ > ‘Configure (project name)’,
select ‘Remote’, choose ‘+’ > Add Remote
Name : origin
Address : git@gitlab.com:xxx/yyy.git
(Curiously it appears after this in the XCode prefs)
Don't forget: using SSH, the password is the one you used (keygen) when building the key !