Later this week, Apple (AAPL -0.82%) will get a chance to remind investors why its business is worth nearly $1 trillion. The tech giant is scheduled to report its fiscal second-quarter results on April 30. 

The earnings report comes at a time when Apple is facing headwinds in its iPhone business. The company's latest round of new iPhones is failing to drive year-over-year growth in the important segment, putting the pressure on the rest of the business to make up for the declining sales.

Ahead of Apple's second-quarter results, here's a preview of several items worth checking on.

Apple CEO Tim Cook kicks off Apple’s March 2019 event.

Apple CEO Tim Cook. Image source: Apple.

Expect revenue to drop

Following a sharp year-over-year decline in iPhone revenue in the first quarter of 2019, management must be expecting the segment to weigh on results again in Q2. Apple guided for total second-quarter revenue between $55 billion and $59 billion, representing a 3% to 10% decrease compared to the year-ago quarter.

Notably, the midpoint of this guidance range suggests management expects its slumping revenue to worsen in Q2 compared to Q1, as revenue fell 5% year over year in Q1. But with the high end of Apple's guidance range implying just a 3% revenue reduction, there's a chance the company's top-line headwinds could moderate during the quarter.

How's Apple doing in Greater China?

While the iPhone has been the main product segment behind Apple's revenue decline, management said in the first-quarter earnings call that the product's challenges during the period can be mostly traced to a single market: Greater China.

Capturing the company's challenges in the market, revenue in Greater China tumbled a whopping 27% year over year in the first quarter of fiscal 2019. 

Will the market show signs of recovery in Q2?

CEO Tim Cook was still optimistic about the market in the fiscal first-quarter earnings call, noting record services revenue in the market during Q1. In addition, Cook said over two-thirds of customers in China who bought a Mac or an iPad during the quarter were buying them for the first time. Finally, he pointed out that the company's revenue in the market during the full calendar year of 2018 was up compared to 2017.

"Macroeconomic factors will come and go. But we see great upside in continuing to focus on the things that we can control," Cook said.

Two key catalysts

Accounting for over half of Apple's revenue, falling iPhone sales make year-over-year top-line growth difficult. iPhone revenue dipped 15% year over year in Q1. But revenue from the rest of the company's segments increased 19% year over year. Two segments, in particular, are playing an outsize role in this growth: services and wearables, home, and accessories.

Combined revenue from these segments increased 24% year over year in the first quarter, adding $3.6 billion of incremental revenue compared to the year-ago quarter. Investors should look for similarly strong growth from the segments in Q2.

Apple will report its fiscal second-quarter results after market close on Tuesday, April 30.