The feature, which lets developers reduce the size of their applications, isn’t being supported in the public version of iOS 9.
“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,” explains an Apple developer support page.
It continues: “When a customer downloads your iOS 9 app, they will get the Universal version of your app, rather than the variant specific for their device type. TestFlight will continue to deliver variants for your internal testers. App slicing will be re-enabled with a future software update. No action is needed by you at this time.”
Apple first announced App Thinning, a major developer tool for iOS 9, back at its annual Worldwide Developer Conference earlier this year.
App Thinning allows developers to slim down very large apps by letting developers mark assests for specific device types.
As such, when a user downloads an app, the App Store works out what device is being used, and downloads the assets needed for that particular device.
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The feature was supported on Apple’s TestFlight developer program for a short while, but it’s off limits in iOS 9 for the foreseeable future.
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Check out our iOS 9 features video below: