Apple will have certainly Googled your domain. Without been specific to Apple, it's a common practice of large multinational companies to perform international

Apple will have certainly Googled your domain. Without been specific to Apple, it's a common practice of large multinational companies to perform international searches for registered and unregistered trademarks as well as any common usage of the marks they are interested in using. If any potential registrations, or strong claims on the mark, are found in the same field of business a specialist will probably be contracted to perform a more in depth investigation. I would be surprised if Apple had not taken the time to assess your claims on the HealthKit mark. I can only guess that they did and decided that there was either: a) no conflict between your businesses and hence use of the mark - in which case you should be happy, yet careful not infringe on Apple's usage (keep your eye out for a trademark registration very soon). b) they don't think you have any strong rights on the mark and chose to use it. It may be fun to ask around the office and see if anybody remembers been contacted with out of the ordinary questions regarding the length of your company's operations and asking questions about the HealthKit domain/name in general.