Here are some of the biggest changes Apple reportedly plans to make to the iPhone this year - CNBC

An attendee takes a selfie photograph while arriving for the Apple Worldwide Developers Conference (WWDC) in San Jose, California, U.S., on Monday, June 4, 2018.

David Paul Morris | Bloomberg | Getty Images

Apple will announce new software features coming to iPhones, iPads, Macs, Apple TVs and Apple Watches on June 3, to kick off its annual Worldwide Developers Conference (WWDC). Bloomberg on Monday highlighted a couple features that it says are coming to those platforms.

Software changes in iOS 13, reportedly named "Yukon," are unlikely to be drastic enough to flip falling iPhone sales, but they may refine the experience for Apple's current customers. They could also be used to push the new digital services Apple recently announced, like a video game subscription service and streaming TV shows produced by Apple.

Bloomberg reported Apple is planning to add a new "dark mode" in iOS 13, a feature that's already available for Macs that darkens different parts of the user interface so it's less harsh on eyes, particularly in the evening.

The company is also reportedly planning a new feature that will allow people to use iPads as a secondary display when connected to a Mac. Other features include new multitasking for iPads, tweaks to iMessage that make it more like WhatsApp and a new Health app that "better outlines your daily activity from the day," Bloomberg reported.

Apple's iOS has improved steadily over the years, with recent releases focused on improving battery life and performance on older devices. The company's voice assistant Siri could use a big upgrade, but major changes to it weren't mentioned in the report. Since Apple always rolls out new features to older iPhones and iPads however, iOS upgrades don't usually drive new device sales.