Apple's services revenue topped $9 billion in the March quarter

Apple is closing in on its goal to double software and services revenue by 2020, posting a 31 percent jump for the segment in the March quarter.

The tech giant reported quarterly earnings on Tuesday, including results from its services division, a catch-all category which includes the App Store, Apple Care, Apple Pay, iTunes, cloud services and more.

Revenue for the segment totaled $9.2 billion, compared with $8.39 billion expected.

CEO Tim Cook said in January 2017 that he hoped to double the revenue — then $7.17 billion — by 2020.

Services are still a small part of Apple's sales compared with the iPhone, which booked more than $38 billion during the quarter, but services provide a high-margin, steady and quickly growing revenue stream as smartphone sales are set to slow worldwide.

"Services revenue is a wonderful thing because it is predictable and in my mind it should increase the multiple of the company because it's a much more consistent revenue stream," Ian Winer, analyst at Wedbush, said on CNBC's "Closing Bell" after the report.

Apple has expanded its reach in original content, and recently acquired a magazine subscription app, Texture. Apple Music is also competing against Spotify, which recently went public and is scheduled to report earnings for the first time Wednesday. The company has also opened new avenues for app developers with the release of augmented reality software.

Still, Siri, Apple's smart voice assistant, remains a sore spot for some Apple watchers, who have compared it unfavorably to Amazon Alexa. Apple's long-awaited smart speaker started shipping Feb. 9.