Apple may have exceeded Wall Street expectations for the last quarter, but concerns linger on whether the world's most valuable company could sustain its double-digit growth.

That's because the company's forecast for the holiday quarter is muted and, while he was confident of future prospects, chief executive Tim Cook seemed hesitant to give specifics about how the company would drive growth next year.

"We didn't get great visibility into the central question that we have about Apple," analyst Toni Sacconaghi told the New York Times.

"Can the iPhone grow in fiscal 2016?"

In its earnings report Tuesday, Apple revealed net income last quarter rose to $11.12 billion or $1.96 a share, up 31% from a year ago. With profit up, the company says investors will receive a cash dividend of 52 cents a share.

Overall sales jumped 22% from last year to $51.5 billion.

Those numbers are impressive, considering that Wall Street had expected profit of only $1.88 a share and revenue of $51.11 billion.

What drove Apple's growth was the strong demand for iPhones. The company sold 48 million iPhones worldwide last quarter, up 22% from a year ago. Money it generated from the device was even bigger, as customers bought more expensive phones. It was up 36% from last year.

Sales of Macs hit an all-time high, rising 3%. Apple's "other products" category, which includes the Apple Watch, jumped 61% from a year ago.

But iPad sales were down 20% to less than 10 million units. This is the 7th consecutive quarter that sales of the tablet have fallen.

Sales in what Apple calls Greater China did not disappoint. They nearly doubled from a year ago to $12.52 billion, despite a slowing economy. The region is Apple's second-biggest market behind North America, and may become its biggest.

For the current holiday quarter, Apple sees revenue of between $75.5 billion and $77.5 billion. That takes into account a stronger dollar that has hindered the growth of global companies.

The New York Times reports Wall Street has expected something bigger, saying the low end of the forecast amounts to a soft growth of below 4% from a year earlier.

In an earnings call, Cook said this was not a cause for concern. He said that, barring effects of currency fluctuations, Apple would grow between 8% and 11% this quarter.

On questions about growth prospects in 2016, Cook said: "We don't guide beyond a quarter."

Investors, who had gotten used to huge profits as a result of the company's past successes, took that asa cue. After initially rising on strong quarterly results, the price of Apple's stock closed flat Tuesday.