Question

I have some objective-c code I’m converting from iPhone to iPad. CFGregorianDate is used throughout for date functions. I have never used it, preferring to use NSDate.

I want to take the date and format it so I get the full month name, using the format string “MMMM”, which I don’t seem to be able to do using CFGregorianDate.

What’s the difference between the two, and does it make any difference in usage?

Answer 1

From the docs:

CFDate is “toll-free bridged” with its Cocoa Foundation counterpart, NSDate. What this means is that the Core Foundation type is interchangeable in function or method calls with the bridged Foundation object. In other words, in a method where you see an NSDate * parameter, you can pass in a CFDateRef, and in a function where you see a CFDateRef parameter, you can pass in an NSDate instance. This also applies to concrete subclasses of NSDate.

So, no difference in usage, really. The main difference is that CFDate and its subclasses are legacy types.

However, as has been pointed out, CFGregorianDate is extremely different from CFDate. It doesn’t store a timestamp but rather the year, month, day, hour minute and second as separate integers.

So your best bet is to create a method like cfGregorianToNSDate: in which you parse these integers and construe a new NSDate object.