Starbucks is rolling out an option for users to order and pay for food and drinks via a mobile app. Currently the app is only available for those living in Portland, Ore.

The app allows users to browse the coffee chain's menu, select what they want to order, then choose a store for pickup. Users can pay straight from their device.

"Store locations appear based on the GPS functionality of a customer's iPhone. Upon first use, customers will be asked to accept location services allowing Starbucks to identify the nearest location offering Mobile Order & Pay," said the company in a statement. "If customers choose not to accept location services, they will not be able to use the Mobile Order & Pay feature but will have access to the Starbucks Mobile Menu."

Apart from being limited to Portland, the app is also only available to iOS users, although it will be available to Android users and more areas as it continues to roll out in 2015.

Starbucks also announced it would begin offering beer, wine and evening snacks to customers at 3,000 of its 11,900 locations around the country. The move is expected to help the company get around $1 billion in extra revenue. The company will also be expanding food choices, in particular during lunch hours.

Starbucks' American unit had a traffic gain of only 1 percent in the last quarter, much smaller than the 5 percent from the same quarter last year. Despite this, an increase in food sales has helped balance out the slowing gains in traffic.

One reason for the slowing of gains is likely the shift in customer attention to shopping online rather than in brick-and-mortar stores. Experts suggest the customer shift of attention may be intensifying due to a 6 percent drop in spending at stores in the U.S. during Thanksgiving weekend. That slowing of traffic is expected to continue into the rest of the holiday season.

Starbucks isn't only focusing on its U.S. efforts, however. The company also plans to double its offerings in China by 2019, bringing the number of stores in the country to 3,000.

Last but not least, the company is planning on debuting express stores, coffee trucks and "reserve shops," which will offer premium coffee that is sourced from smaller farms.