Indeed, this solves my problems.
The last difficulty whas that the displayed time was tho hours behind, but it took me some time to realize it was a problem with the settings of the clock in freebsd.
And I have to admit I underestimated the complexity of date and time handling, with the possibilities given by classes as NSTimezone, NSCalendar, NSDateFormatter and NSDate.
Systempreferences is working perfect for Date & time settings.
I do have the impression that NSDateformatter is not working 100 % correctly, but I will need some more experiments.