Developers submitting new apps and updates to the App Store will be required to optimise them for iOS 7 from 1 February, Apple has announced.
The post on its developer portal also stated that new apps must be built using the latest version of Xcode 5 in order to enable new features like backgrounding application programming interfaces (API).
As of 15 December, Apple reports that 76 per cent of devices have adopted iOS 7 since its launch in September. According to the company, 20 per cent of users still run iOS 6, while 4 per cent use even earlier operating systems.
In its efforts to encourage developers to update older apps, Apple has outlined the steps needed to be taken to redesign their apps so that they fit with the new aesthetic. On its interface guidelines for developers designing new apps for iOS 7, the company emphasises deference, clarity and depth as the main characteristics embodying the operating system.
Developers are told to use the themes of iOS 7 to inform the design of the user interface, and to restore details and embellishments with care but "never gratuitously".
"Throughout, be prepared to defy precedent, question assumptions, and let a focus on content and functionality motivate every design decision," Apple instruct.
Other recommendations include using the full screen, incorporating translucent UI elements to hint at the content beneath, and using negative space to highlight important content.