CACurrentMediaTime() / CFAbsoluteTimeGetCurrent() are first of all not deprecated (just check CFDate.h / CABase.h) but return a time interval since system boot so they are guaranteed to be increasing. It's just a fp64 representation of mach_absolute_time() without needing to worry about the time base vs seconds.

Date() / NSDate returns a wall clock time, which is less accurate and not guaranteed to increase uniformly (ie adjusting to time server, user changes time etc)

Also CFAbsoluteTimeGetCurrent explicitly calls out that it isn't guaranteed to only increase. CACurrentMediaTime is monotonic though.

CFAbsoluteTimeGetCurrent also returns seconds since 2001 and is not monotonic, so there's really no reason to use it instead of Date().timeIntervalSinceReferenceDate. The most idiomatic equivalent to the Python time method is definitely some usage of Date(), as time in Python doesn't have monotonic guarantees either.

[1] https://developer.apple.com/documentation/corefoundation/154...

Because they deal with calendar-related stuff that is better accessed through Date.

That is true for CACurrentMediaTime, but that time stops when the system sleeps (https://developer.apple.com/documentation/quartzcore/1395996... says it calls mach_absolute_time, and https://developer.apple.co/documentation/driverkit/3438076-m... says ” Returns current value of a clock that increments monotonically in tick units (starting at an arbitrary point), this clock does not increment while the system is asleep.”)

Also (https://developer.apple.com/documentation/corefoundation/154...):

Repeated calls to this function do not guarantee monotonically increasing results. The system time may decrease due to synchronization with external time references or due to an explicit user change of the clock.

So for this comparison, it is better to use Date().

https://developer.apple.com/documentation/corefoundation/154...

https://developer.apple.com/documentation/foundation/nsdate/...