One feature that the new system for iPhones and iPads will have is a system-wide dark mode, sources close to the development of Apple's mobile operating system told tech website 9to5Mac.
Dark mode, which inverts most interface colours to white text on a black background, is increasingly finding its way onto mobile software from Facebook, Google and Samsung.
While many find the dark colours to be less dazzling at night, battery experts say dark modes on modern phones using OLED screens use less power, as less battery is needed to keep white areas of the screen bright.
Dark mode is already available on macOS, and is a widely anticipated addition for iPads and iPhones.
Other updates in iOS 13 are expected to include new gesture controls and several improved apps such as Reminders and better integration of third-party apps such as email clients and productivity apps.
Apple's voice assistant Siri is also expected to improve and be able to understand commands better. – dpa