CFDate

CFDate objects store dates and times that can be compared to other dates and times. CFDate objects are immutable—there is no mutable counterpart for this opaque type.

CFDate provides functions for creating dates, comparing dates, and computing intervals. You use the CFDateCreate(_:_:) function to create CFDate objects. You use the CFDateCompare(_:_:_:) function to compare two dates, and the CFDateGetTimeIntervalSinceDate(_:_:) function to compute a time interval. Additional functions for managing dates and times are described in Time Utilities

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. See Interchangeable Data Types for more information on toll-free bridging.