An unreleased iPhone multitasking interface, unseen for over a decade and a half, was brought back to life with the help of AI and emulation.
Before the iPhone got the app switcher we all know and love, Apple made multitasking available through a sliding drawer that popped up at the bottom of the screen. However, the company experimented with a much more impressive design, showing open apps as on-screen cards.
After AppleInsider described an Expose-like interface in early 2010, a special build of iOS 4 was discovered on an iPhone 4 prototype the very next year. In the decade that followed, nobody had ever showcased the card-like multitasking design – until an emulator developer used AI to bring the scrapped UI back to life.
In a Mastodon post, Steve Troughton-Smith shared a video of the unreleased multitasking UI, with a previously unknown build of iOS 4 running on a QEMU fork. The build number seen in the video is 8A218, which would make the operating system only slightly newer than the 8A216 build uncovered in 2011.
Artificial intelligence appears to have played a crucial role in getting the special build of iOS running. In a statement to AppleInsider, the developer said that “any old iOS build you can find is now something you can emulate, thanks to AI-assisted emulator development.”
Based on available information, it looks as though this rare build of iOS came from a prototype unit rather than an internal restore bundle. In short, someone took the root filesystem of a development device or prototype iPhone, and then ChatGPT made it boot in QEMU.
The video itself offers a rare look at the Expose-style interface Apple was experimenting with during the iOS 4 development cycle. Each open application appeared as a card, taking up part of the screen. By double-tapping the Home button, users could easily switch between apps without scrolling.
Though the iPhone never got this card-style multitasking UI, Apple did end up bringing it to the iPad, in a manner of speaking. Before iPadOS 26 gave the platform windowed multitasking, the iPad app switcher similarly displayed open applications in the form of swipeable cards.
Still, the older iPadOS implementation is not identical to the planned iOS 4 multitasking UI, with app names appearing at the top rather than the bottom, for instance.
If it wasn’t for artificial intelligence, we might never have seen the initial idea in action once again. The November 2026 video highlights the potential AI holds in the area of preserving unreleased or scrapped software designs.
Apple itself has recognized the significance of AI-assisted coding, with Xcode 27 introducing support for AI agents. Internally, Apple employees use AI for development as well, though the company has reportedly cut funds for third-party AI from $300 to $200 per engineer.