One of our most oft requested features was to add Void of Course Moon to iPhemeris. We are happy to announce that Version 2.1 of iPhemeris for Mac OSX was released March 1, 2016 and adds this feature.
You'll find it at the bottom of the monthly Ephemeris and Dec/Lat tables. It shows the date, time, planet and aspect of the last major aspect made by the Moon (Conjunction, Sextile, Square, Trine, Opposition) to a major planet, and the subsequent time of Lunar Ingress into the next Sign. Times are given for GMT and Local Time (whatever that is on your device).
The Void of Course Moon period is the period of time between the last aspect made and the time of subsequent Lunar ingress into the next sign. In the illustration shown above, on the first row you can see that the last aspect was a conjunction to Mars at 14:55 EST followed by the subsequent Lunar ingress into Sagittarius at 18:56 EST. The Void of Course period was between 14:55 and 18:56, or about 4 hours and 1 minute.