Not long after the iPhone came out, skeptics questioned how much appeal the costly device and related wireless service would have in countries like China with lower income levels. On Tuesday, Apple provided the answer: A lot.

The company reported Tuesday that soaring sales of the iPhone, especially in China, helped Apple nearly double its profit in the company’s fiscal second quarter.

Apple said it sold 35.1 million iPhones in the quarter, an 88 percent increase from the period a year ago. It sold 11.8 million iPads, more than double the number it sold in the same quarter last year.

“It was an incredible quarter in China,” Timothy D. Cook, Apple’s chief executive, said in a conference call with Wall Street analysts. “It is mind-boggling that we could do this well.”