Previewed at WWDC, launching in the fall.
Apple Confirms HealthKit Bug, Promises Fix by End of September
While details on the issue are still unknown, Apple has confirmed to Tim Bradshaw of Financial Times that it has discovered a "bug" in HealthKit that will require a software update to fix. Unfortunately, Apple is not necessarily promising an immediate turnaround on the fix, saying only that the company is aiming to "have HealthKit apps available by the end of the month".
iOS 8 is available now to owners of recent-generation iOS devices, and will be included on the iPhone 6 and 6 Plus when they officially launch on Friday. Aside from Health, iOS 8 includes a number of other features such as a new QuickType keyboard with word suggestions, support for systemwide third-party keyboards and Touch ID integration, Photos and Messages improvements, and Continuity features to make iOS device and Macs work more smoothly with each other.