iOS 27 Drops Legacy iPhones While Trimming Code for Battery Gains

Apple will unveil iOS 27 at WWDC on June 8, and the update could abandon four older iPhone models. The move forces users with those devices to either stay on iOS 26 or upgrade hardware.

The update is code‑named “Rave” and promises a sweeping internal cleanup, Mark Gurman reports. Apple aims to strip legacy code, rewrite core features, and nudge apps toward better performance. Gurman likens the effort to the Snow Leopard revamp for macOS, a strategy that historically shaved seconds off boot time and reduced memory use. The headline benefit is a snappier OS and measurable battery gains, though Apple has not promised a marketing spin.

Dropped Device Support

Rumors circulating among developers suggest iOS 27 will no longer support four iPhone models. Apple has not confirmed which devices are affected, but the pattern matches past major releases that retire the oldest hardware. Users of those models will see the update option disappear from Settings, forcing them to remain on iOS 26 or replace their phones.

The decision raises a familiar tension: Apple pushes new features while shrinking the upgrade path for legacy users. For engineers, the loss of older devices simplifies testing and allows Apple to drop legacy APIs. For power users, it means a forced hardware refresh sooner than expected, a cost that many will weigh against the promised performance gains.

The Code‑Cleanup Strategy

Rave’s centerpiece is a systematic removal of dead code. Gurman says engineers are excising obsolete libraries, consolidating duplicated frameworks, and tightening system calls. The effort mirrors the Snow Leopard project, which removed billions of lines of code to streamline the OS.

Beyond sheer size reduction, the cleanup targets battery‑draining subsystems. Early benchmarks suggest a modest improvement in standby time, though real‑world gains will depend on user habits. Apple is unlikely to advertise the battery bump directly; the company prefers users to discover a longer‑lasting device through daily use.

AI and New Hardware Outlook

iOS 27 also carries Apple’s delayed AI ambitions. The revamped, chatbot‑style Siri announced in June 2024 missed its iOS 26 deadline and is now slated for inclusion in iOS 27. Gurman notes that Siri’s new capabilities will be unlocked via software rather than a dedicated chip, meaning older devices that receive the update could see a modest AI boost—if they survive the support cut.

Apple is simultaneously gearing up for two new hardware categories: a touchscreen MacBook Pro and its first foldable iPhone. Both concepts rely on a clean, efficient OS foundation. By pruning iOS now, Apple reduces the risk of legacy bottlenecks when those products ship, ensuring a smoother transition for developers targeting the next generation of Apple hardware.

Interface Tweaks and User Experience

While Rave’s primary focus is under the hood, Apple will also slip in subtle UI adjustments. Gurman says the changes are “nothing as dramatic as the Liquid Glass overhaul introduced with iOS 26.” Expect minor layout shifts, refined animations, and a refreshed control‑center layout that feels marginally more responsive.

These tweaks aim to reinforce the perception of a “snappier, more responsive” system without alienating users accustomed to iOS 26’s look. For power users, the adjustments are likely to go unnoticed unless they compare side‑by‑side. For the broader audience, the smoother feel may be the most visible sign of the deep‑clean effort.

What to Watch

The next WWDC keynote will reveal the exact list of iPhones left out of iOS 27, and it will confirm whether Apple markets the battery improvements. After the launch, watch early adopter benchmarks for real‑world battery life and Siri response times. Finally, keep an eye on the timeline for the touchscreen MacBook Pro and foldable iPhone—both will depend on the leaner OS foundation Rave creates.