Fix Your Damaged Mac App Store App by Parsing the App Store Receipt Dates Correctly

If your customers get this message when downloading your app from the Mac App Store:

XYZ is damaged, remove it and download again from App Store.

… it might be because you’re parsing the App Store receipt dates wrong!

Apparently, Apple began to change Mac App Store receipt date formats recently:

  • Old format: 2020-10-03T07:12:34Z
  • New format: 2020-10-03T07:12:34.567Z

When you parse receipt dates, account for both variants. To make things easier for you, strongly consider to use ISO8601DateFormatter (NSISO8601DateFormatter in Objective-C) which should (!) handle multiple variants of ISO-8601 dates for you.

Huge thanks to Frank Illenberger of ProjectWizards, makers of project management software Merlin Project, for figuring this out!

See also:

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