McDonald's has started to test mobile ordering of food from some of its restaurants, with customers in areas of Washington and California among the first to try out the iOS app's new feature, which the fast food chain hopes to spread globally later this year.

Customers will be able to place their order from the iOS app before arrival, with the app tracking the user's location to make sure the right restaurant, according to Reuters. The location tracking will also allow the restaurant to start preparing the order a short time before the customer is expected to turn up, timing the order's completion for their arrival to keep the food as fresh as possible.

Before orders are delivered to the restaurant's kitchen, customers will have to confirm and pay for it via the app, though the final version will also include options for table service, counter pickup, a drive-through pickup, and curbside delivery. AppleInsider has asked for clarification on whether this will use Apple Pay or some other payment method for Apple devices.

Chief Executive Steve Easterbrook suggests that if 20 percent of drive-through customers used curbside delivery and another 20 percent used the drive-through lanes for pickup only, restaurants would be able to serve another 20 cars per hour on average. Drive-through business is the biggest source of revenue for the company in the United States, accounting for approximately 70 percent of sales.

Mobile ordering is live at 29 restaurants in Monterey and Salinas, California as of Wednesday, with an extra 51 restaurants in Spokane, Washington set to join the pilot scheme on March 20.

Following the trial, McDonald's expects to start rolling out the app to most of the other 14,000 restaurants in the United States, as well as 6,000 located in Canada, the United Kingdom, France, Germany, China, and Australia later this year.

Initially announced as part of a financial release at the beginning of March, McDonald's digital expansion will also see a greater presence of ordering kiosks in restaurants. The kiosks will be able to bring up the customer's favorite and previous orders from the app, as well as preferred payment methods, to speed up the ordering process.