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Canceled iOS 4 multitasking UI revived with AI-assisted emulation

A long-lost card-style multitasking interface from the iOS 4 era has been shown running again, after a developer used AI to boot a rare prototype build of the operating system in an emulator.

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Published 2 min read

Illustration of an iPhone screen showing open apps as cards in a multitasking view

Key takeaways

  • An unreleased card-style multitasking interface from the iOS 4 era has been shown running in an emulator for the first time.
  • The build, numbered 8A218, appears to come from a prototype iPhone and is slightly newer than the 8A216 build found in 2011.
  • The developer says AI-assisted emulator development made it possible to boot the old build in QEMU.
  • A similar card-based app switcher later appeared on iPad, though the two designs differ in details.
In this article
  1. A scrapped iPhone interface comes back to life
  2. How the rare build was recovered
  3. Where the idea lived on
  4. Why AI-assisted preservation matters

A scrapped iPhone interface comes back to life

An iPhone multitasking design that Apple never shipped has been demonstrated again, more than a decade after it was last seen. According to AppleInsider, developer Steve Troughton-Smith posted a video on Mastodon showing an unknown build of iOS 4 running in an emulator, complete with the unreleased interface.

The design worked like Exposé on the Mac. Instead of the sliding drawer Apple shipped in iOS 4, open apps appeared as cards spread across the screen. Double-tapping the Home button let a user jump between apps without scrolling through a list.

How the rare build was recovered

The build shown in the video carries the number 8A218. That makes it only slightly newer than the 8A216 build found on an iPhone 4 prototype in 2011, shortly after AppleInsider first described the Exposé-style design in early 2010.

Until now, nobody had shown the card-based interface in action. AppleInsider reports that the system image appears to come from a prototype device rather than an internal restore file. The developer told the site that ChatGPT helped make the build boot in QEMU, an open-source emulator.

Where the idea lived on

Apple never brought card-style multitasking to the iPhone, but a version of the idea reached the iPad. Before iPadOS 26 introduced windowed multitasking, the iPad app switcher showed running apps as swipeable cards.

The two designs are not identical. In the older iPadOS switcher, app names appear at the top of the screen rather than the bottom, so the scrapped iPhone concept remains distinct.

Why AI-assisted preservation matters

Illustration: AI, Apple logo, code, streaming and the labels iOS 4, Apple, Emulation

The video shows how AI tools can help preserve software that would otherwise stay hidden. AppleInsider notes that without AI assistance, the scrapped design might never have been seen running again.

Apple has also embraced AI in its own development work. Xcode 27 added support for AI agents, and employees reportedly use AI internally. The company has, however, reportedly reduced its budget for third-party AI services from $300 to $200 per engineer.

Sources

  1. Apple's canceled iOS multitasking UI lives on, with AI-enhanced emulationApple Insider

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