Sales of the iconic mobile phone in China advanced 18% in December from the year-earlier month, Reuters reported.
Apple's stock at last check was up 2.3% to $310.33 and earlier in the day had reached an all-time high of $310.43, valuing the company at $1.4 trillion. Shares have doubled in the past year.
Citing data from the China Academy of Information and Communications Technology and the news service's own calculations, Reuters pegged the raw number of sales at 3.2 million, up from 2.7 million a year earlier.
Throughout last year, Apple discounted the phones and arranged financing in an effort to lift sales. CEO Tim Cook has touted the China marketing efforts, Reuters reported.
"This is a larger jump, [2 percentage points] more, than expected," said Dan Ives, managing director for equity research at Wedbush.
It's a "very bullish data point and speaks to our China rebound thesis for" the Cupertino, Calif., tech giant, Ives said.
The analyst has an outperform rating and $350 price target on Apple.
Apple has faced tough competition in China, particularly from offerings from Huawei Technologies, the Shenzhen telecom-tech provider.
Huawei "doubled down on China in the third quarter," Melissa Chau, associate research director at International Data Corp., said in a November report. The report said Huawei had "shifted focus to its domestic market, particularly in lower-tier cities."
On Jan. 28, after the stock market closes, Apple is scheduled to report fiscal-first-quarter results.
A survey of analysts by FactSet Research estimates the company earned $4.53 a share on revenue of $88.22 billion. Of that revenue figure, analysts peg worldwide iPhone sales at $51.24 billion, or 58% of the total.