Apple has released iOS 27 beta 4 to developers, marking the fourth preview of the next major iPhone operating system. Following the initial unveiling at WWDC 2026, this beta continues to refine the platform with a focus on Siri AI, Apple Intelligence, Liquid Glass design refinements, and numerous quality-of-life improvements. The build number for beta 4 is 23G71, and it is available now for enrolled developers via the Settings app under General > Software Update > Beta Updates.
As with any beta release, users are advised not to install it on primary devices due to potential performance issues, including bugs, battery life fluctuations, app compatibility problems, and other rough edges. Apple is expected to continue refining the software through the summer, with a public beta already available and a final release slated for September alongside the new iPhone lineup.
What's new in iOS 27 beta 4
This beta introduces several notable changes and fixes. The most visible update is a new splash screen for Siri AI that appears when invoking Siri from the Dynamic Island or by swiping down on the Home screen. This visual cue aligns with Apple's push to make AI interactions more prominent and intuitive. Additionally, the controversial depth effect bug that was introduced in beta 3 has been fixed. This bug had caused visual glitches on wallpapers, but users reported enjoying the unintended aesthetic while it lasted.
Siri's voice capabilities receive significant improvements in this beta. Two enhanced voices now fully support pace and expressivity sliders, allowing for more natural-sounding interactions. Five legacy voices still show these sliders as 'coming soon,' indicating ongoing work to expand the feature. The Control Center now includes support for the new adaptive mode slider for AirPods Pro, giving users more granular control over noise cancellation and transparency modes.
The TV app gains a smart download feature that automatically downloads upcoming episodes as a user progresses through a season, ensuring seamless viewing without manual intervention. The Photos app introduces a new 'Zoom Photos to Fill' setting that optimizes images with aspect ratios similar to the device display, reducing letterboxing. A new 'Preview' setting for the Siri app allows users to adjust how many lines of text appear in chat lists, similar to existing options in the Mail app.
Dual-battery code hints at foldable iPhone Ultra
Perhaps the most intriguing discovery in iOS 27 beta 4 is potential code references to a dual-battery configuration. This hardware feature has been widely speculated in relation to a future foldable iPhone, often referred to as the iPhone Ultra. A dual-battery setup would allow for a thinner profile and more efficient power distribution in a folding device. While Apple has not confirmed such a product, these code hints suggest ongoing development. The foldable iPhone could launch as early as 2027, but analysts caution that beta code does not guarantee near-term release.
Background and context of iOS 27
iOS 27 represents a major leap forward for the iPhone platform. The update centers around three pillars: Siri AI, which leverages on-device machine learning for context-aware assistance; Apple Intelligence, a suite of advanced analytics and personalization features; and Liquid Glass, a design language that introduces translucent, dynamic UI elements. These features require modern hardware, with support extending to iPhone 11 and later, iPhone SE 2 and newer, while Siri AI and other Apple Intelligence functions are limited to devices with the A17 Bionic chip or newer.
The beta process for iOS 27 began in June, with the first beta focusing on foundational changes. Beta 2 introduced the Liquid Glass interface and new Siri capabilities, while beta 3 added expanded Apple Intelligence features but also introduced the depth effect bug. Beta 4 now stabilizes the experience while adding new polish. Developers can submit feedback through the Feedback Assistant app, and Apple continues to refine the OS based on community input.
The public beta, released last week, allows non-developers to test the software, though with the same caveats about stability. As summer progresses, subsequent betas are expected to address remaining issues and optimize performance ahead of the fall launch. The final release will coincide with new iPhone models, likely including the iPhone 17 series, which are rumored to feature improved camera systems and a new A19 chip.
Detailed analysis of key features
The Siri AI splash screen is more than a cosmetic change; it signals Apple's intent to make AI a core interaction method. Users can invoke Siri from the Dynamic Island, which now responds with an animated splash that provides visual feedback before the assistant listens. This reduces ambiguity and makes the system feel more responsive. The enhanced voices with working pace and expressivity sliders are part of a broader effort to humanize Siri, making it suitable for conversational tasks like reading messages, telling stories, or guiding meditation.
The depth effect fix is a welcome correction for photographers who rely on the feature for portrait-style wallpapers. Beta 3 had introduced an issue where depth maps were incorrectly applied, causing elements to blur in unintended ways. Beta 4 restores proper functionality, ensuring that foreground subjects remain sharp against bokeh backgrounds.
AirPods Pro users will appreciate the adaptive mode slider in Control Center. This feature allows real-time adjustment between Active Noise Cancellation (ANC) and Transparency modes, with a middle ground that adapts based on ambient noise. The slider is a refinement of the adaptive audio feature introduced in iOS 26, giving users more manual control over their listening experience.
The TV app's smart download capability is a subtle but powerful time-saver. For binge-watchers, manually queuing episodes can be tedious. This feature learns watching habits and pre-downloads the next episode, ensuring playback starts instantly when the current one ends. It leverages machine learning to predict which series a user is actively following.
In Photos, the 'Zoom Photos to Fill' setting addresses a common frustration when viewing images with aspect ratios that don't match the device's screen. Instead of showing black bars, the system intelligently crops the image to fill the display. Users can toggle this setting on or off, with an option to fine-tune the crop for each photo.
The Siri app Preview setting is a personalization option that lets users choose between compact and expanded chat lists in messaging apps. Similar to how Mail offers a preview line count, this setting adjusts the number of lines of text shown for each conversation, allowing users to see more messages at a glance or more context per message.
Potential for foldable iPhone Ultra
The dual-battery code references found in beta 4 are the strongest evidence yet of a foldable iPhone. A dual-battery design would allow the device to maintain a slim profile when folded while providing ample power. The two cells could be placed in separate halves of the device and managed intelligently to balance charge cycles and heat distribution. This approach is common in existing foldable phones from competitors like Samsung and Huawei. If Apple is indeed working on a foldable, iOS 27 would need to support a different form factor, including multi-window multitasking and seamless display transitions. The code suggests that such support may be under development, though it might not be ready for the initial iOS 27 release.
Industry observers note that Apple typically introduces major hardware changes alongside software optimizations. A foldable iPhone could be announced in 2027, giving Apple time to perfect the hinge mechanism and software experience. The dual-battery code could also be for other future devices, such as a foldable iPad or a larger iPhone Pro Max model. However, the specificity of the code hints at a foldable design.
Broader implications for the iPhone ecosystem
iOS 27 beta 4 continues Apple's trend of integrating AI into every aspect of the user experience. The Siri AI improvements, combined with Apple Intelligence, position the iPhone as a more proactive and personalized device. The Liquid Glass design language adds a layer of visual sophistication that differentiates iOS from competing platforms. These changes are likely to drive consumer interest in upgrading to newer iPhone models, especially those that support the full feature set.
Developers should test their apps with beta 4 to ensure compatibility, especially with the new Siri APIs and Control Center enhancements. The TV app's smart download feature may require server-side updates, but overall the beta appears stable enough for development testing.
As Apple continues to refine iOS 27, users can expect additional betas with more fixes and features. The final release will be a defining moment for the iPhone, cementing the role of AI in everyday computing and setting the stage for future hardware innovations like the foldable iPhone.
Source: 9to5Mac News