What does era mean in NSDateComponents?

Question

Sorry if this seems to be a silly question, but Ive just come across this part of NSDateComponents, and was puzzled as to what it actually represents. My mind was wondering if Objective C actually has a list of era's built into it, like the Era of Diocletian or the Seleucid Era, but then I dismissed this thought as being silly.

So what era does the NSDateComponent era actually refer to? Is it just a matter of BC / AD, or is there more to it?

Answer 1

Yes, in the Gregorian Calendar there are two eras, BC and AD.

Apple Dev: Historical Dates

Answer 2

It's BC/AD for the Gregorian calendar, but there are other eras in other calendars (e.g., Japanese).