iPhone 6 review
A bug has been discovered in the HealthKit feature of the iPhone 6's iOS8Apple

The introduction of HealthKit, one of the signature features of Apple's latest iPhone operating software, has been delayed, with the company announcing they had found a bug.

The health and fitness application was due to launch on Wednesday as part of Apple's iOS8, and its absence will have disappointed many who were eagerly awaiting the upgrade.

"We discovered a bug that prevents us from making HealthKit apps available on iOS today. We're working quickly to have the bug fixed in a software update and have HealthKit apps available by the end of the month," Apple said in a statement.

HealthKit is a digital hub of bodily data, around which a myriad of smart devices and wearable tech are based. Smart watches and bands will serve to collect a range of data on the user's body, from blood-glucose levels to caffeine levels – and send it to their smartphone to be stored.

HealthKit also allows users to send their fitness data to doctors, app developers and just about anyone.

Apple has also pulled healthcare apps that connect with HealthKit, including MyFitnessPal.

"The MyFitnessPal app, which supports integration with Apple's HealthKit, was temporarily removed from the Apple Store this morning to address some minor issues," MyFitnessPal said in a statement emailed to Reuters.

"We are working with Apple on a solution and will have an updated version of the app, without the HealthKit piece (for the time being), back on the App Store shortly," the company said.

The bug is a blow to Apple's big OS launch ahead of the new iPhone 6 release on Friday (19 September).