Will Apple (AAPL) CEO Tim Cook Deliver Up to This One Big Promise He Made? - TheStreet

Apple (AAPL) - Get Report will post its fourth quarter earnings results Tuesday afternoon and UBS analyst Steve Milunovich discussed what investors can expect when the tech titan reports.

One metric which will be dissected is the unit growth of Apple's most popular product, the iPhone. Unit growth, "is important in the sense that Tim Cook promised it last quarter, so we are only up one or two million units year-over-year," Milunovich noted during CNBC's "Squawk on the Street."

However, he added that far more people are anticipating Apple's release of its iPhone 8. "So, I think the street is expecting a relatively weak guide for the March quarter. But, It is all about setting up for the net product cycle."

While the iPhone is a maturing product, the installed base is still growing, and with the much-anticipated iPhone 8 upcoming, that could translate into double-digit unit growth for fiscal 2018, Milunovich said.

WATCH MORE: Will the Apple's iPhone 8 include wireless charging?

The other key metric investors will hone in on is sure to be revenue from its services. Many have called for Apple to start to demonstrate the capabilities of being a services-oriented company.

"I think the services are really important, certainly more important than what is happening in the Mac area. We expect about 40% growth in the app store which is very high margin," Milunovich stated.

But, he reiterated his view of Apple being a "platform company."

"Primarily, it is selling hardware and the services there support the premium price they get for the hardware," he explained. "So, one must be careful; it is not becoming a services company. The services are very much attached to the hardware sales, but it's a great revenue line with a high margin."

(Apple is a core holding of Jim Cramer's charitable trust Action Alerts PLUS. See all of his holding with a free trialhere.)