Apple has been crowned king of the wearable band market after Q2 shipments surpassed the four million mark, according to Canalys.
Apple launched the device launched in the spring and sold 4.2 million units in Q2, "easily overtaking" offerings from FitBit, Xiaomi and other smartwatch vendors.
The analyst said Apple's success has come despite its "significantly higher pricing" compared with its rivals, and against a backdrop of supply-chain trouble which stalled shipments in its first months in the market.
But the vendor should not rest on its laurels if it wants to maintain its success, Canalys said.
"The Apple Watch is the most sophisticated smartwatch to date, and it has proved popular with Apple fans worldwide," said Canalys' vice president Chris Jones. "But Apple and other vendors still face important challenges to make the smartwatch 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."
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