NEW YORK – Apple Inc. on Wednesday reported another exceptional quarter, nearly doubling its net income and far exceeding analyst estimates on the strength of the seemingly unstoppable iPhone.

However, sales of Apple’s big new product, the iPad tablet computer, came in below expectations. Manufacturing constraints prevented Apple from selling more of them. Chief Financial Officer Peter Oppenheimer said progress is being made on expanding iPad production.

Apple said net income for its fiscal second quarter, which ended in March, was $5.99 billion, or $6.40 per share, up 95 percent from $3.07 billion, or $3.33 per share, a year ago. Analysts polled by FactSet expected earnings of $5.37 per share.

Revenue was $24.7 billion, up 83 percent from $13.5 billion a year ago. Analysts were expecting $23.4 billion.

The results were lifted by the record sale of 18.65 million iPhones, millions more than analysts had expected.