Apple's upcoming smartwatch is expected to run a custom version of iOS that will support third-party applications. And to ensure that there are plenty available when the device goes on sale, Apple has reportedly already provided trusted developers with its new iWatch SDK.

"A small handful of high-profile social network and services companies with apps on the iPhone and iPad App Store have already been seeded with a pre-release version of the Apple SDK (Software Development Kit) for wearables under strict non-disclosure agreements," 9to5Mac reports.

The SDK was supposedly seeded "very recently," but it's thought Apple wants to showcase some third-party wearable apps as early as this week. Recent reports have claimed the Cupertino company will unveil the iWatch — if that it its real name — alongside the iPhone 6 on Tuesday before making it available early next year.

This is something Apple has done many times in the past, of course. When it announced the original iPad back in 2010, for instance, Scott Forstall invited Gameloft, EA, and The New York Times up onto the stage to demonstrate apps they had already built for the new device. The company is always keen to showcase not only what its devices can do with its own software, but the added functionality that others can bring to them, too.

The iWatch is expected to be closely integrated with iOS 8 and services like HealthKit and HomeKit, and like rival smartwatches, it's likely to have built-in sensors that will track steps and monitor your heart rate. 9to5Mac claims it will also have NFC "to act as a conduit for Apple's upcoming mobile payments platform."

Apple has been working with fashion and fitness experts to design the device, which is expected to be as attractive as everything else it creates. I don't know about you, but I'm even more excited for Tuesday's event knowing Apple's first wearable could be making an appearance.