class CFPropertyList::CFDate

def set_value(value,format=CFDate::TIMESTAMP_UNIX)

set value with timestamp, either Apple or UNIX 
def set_value(value,format=CFDate::TIMESTAMP_UNIX)
  if(format == CFDate::TIMESTAMP_UNIX) then
    @value = Time.at(value)
  else
    @value = Time.at(value + CFDate::DATE_DIFF_APPLE_UNIX)
  end
end