​Apple's iOS 9 cure for storage hungry apps is put on hold

The iOS 9 feature that would have meant more space on your iPhone is not currently available.

Apple has delayed App Slicing, an iOS 9 feature that promised to cut the fat out of apps and give iPhones, iPads and iPods more available storage.

App Slicing was meant to be available for iOS 9 apps and is the chief component of a process Apple calls "app thinning", the Cupertino company's way of optimising iOS to enable faster downloads and more storage space.

Apple announced on Thursday that the feature is now on hold due to a glitch with iCloud backups.

"App slicing is currently unavailable for iOS 9 apps due to an issue affecting iCloud backups created from iOS 9 where some apps from the App Store would only restore to the same model of iOS device," Apple said.

For now, Apple will continue to deliver the traditional Universal version of apps rather than sliced apps.

"App slicing will be reenabled with a future software update. No action is needed by you at this time," it told developers.

The optimisation will eventually benefit all iOS 9 devices, but it will be particularly handy for owners of the 16GB variants of the iPhone, iPad and iPod, who probably need to delete apps and transfer content to reclaim available storage.

The key difference between "universal apps" and those that have been sliced is that the former include resources for multiple devices with different screen sizes and resolution.

With App Slicing, the App Store automatically carves out the necessary image resources to suit the resolution of a specific iPad and iPhone model.

As Apple explains in its developer documents: "Slicing is the process of creating and delivering variants of the app bundle for different target devices. A variant contains only the executable architecture and resources that are needed for the target device. You continue to develop and upload full versions of your app to iTunes Connect. The App Store will create and deliver different variants based on the devices your app supports. Image resources are sliced according to their resolution and device family. GPU resources are sliced according to device capabilities. For tvOS apps, assets in catalogs shared between iOS and tvOS targets are sliced and large app icons are removed. When the user installs an app, a variant for the user's device is downloaded and installed."