The Apple Watch has become the bestselling wearable band, with 4.2 million shipments during the second quarter of this year, new research has claimed.
The report from Canalys said Apple has overtaken rivals including Fitbit, Xiaomi and Samsung, despite the comparatively higher price of the Watch.
Researchers said its Watchkit SDK was "delivered quickly and comprehensively" and offers developers a strong platform to build upon without battery life suffering.
However, it criticised Apple for missing the key Q4 trading season, with the Watch only going on sale in April this year. It said potential sales were also damaged by supply constraints in the weeks after launch.
Chris Jones, VP and Principal Analyst at Canalys, commented: "The Apple Watch is the most sophisticated smart watch to date, and it has proved popular with Apple fans worldwide. But Apple and other vendors still face important challenges to make the smart watch a breakout hit. Improvements in performance, battery life and sensor integration are needed to make future models more attractive, but it is the quality of third-party apps that will determine whether the Apple Watch will be a long-term success."
Last week, Apple launched its contactless payment service in the UK, the first market it has brought it to outside of the United States. It allows owners of a compatible iPhone or Watch to make payments using their device.
Despite the increasing levels of adoption, research from Gartner last month warned the wearables sector still faced scepticism when it came to the usefulness of devices, as well as their battery life.