How to parse an ISO-8601 duration in Objective C?

I’m looking for an easy way to parse a string that contains an ISO-8601 duration in Objective C. The result should be something usable like a NSTimeInterval.

An example of an ISO-8601 duration: P1DT13H24M17S, which means 1 day, 13 hours, 24 minutes and 17 seconds.

How to parse an ISO-8601 duration in Objective C?