iOS 26.4 Beta 3 Seeded to Developers
Apple has released the third developer betas of iOS 26.4 and iPadOS 26.4. The update continues the focus on security with ongoing heap hardening, while also expanding diagnostic and accessibility features. This release is a critical point for developers to validate app compatibility against the latest SDKs.
The build number for this release is 23E5223f and is bundled with the Xcode 26.4 Beta 2 toolchain, which includes Swift 6.3 and updated SDKs for all platforms. The accompanying Instruments profiler has been significantly overhauled with a new "Run Comparison" feature to identify performance regressions and a "Top Functions" mode. The continued heap hardening effort involves a "type-aware memory allocator" which developers can opt into with the `com.apple.security.hardened-process.hardened-heap` entitlement. To utilize this, the `CLANG_ENABLE_C_TYPED_ALLOCATOR_SUPPORT` and `CLANG_ENABLE_CPLUSPLUS_TYPED_ALLOCATOR_SUPPORT` build settings must be enabled, which rewrites memory allocations to enhance security against zone allocator attacks. Beta 3 addresses several critical bugs from previous builds, including a fix for the Spotlight search lag that often returned no results. It also resolves excruciatingly slow loading times within the App Store and a system-level bug that prevented sending emails from the Gmail app. A significant fix resolves a failure in the end-to-end encryption for RCS messages with Android devices, which previously caused chats to downgrade to unencrypted SMS. Testing for encrypted RCS between iPhones and Android devices began in iOS 26.4 beta 2. While this beta cycle introduces AI-driven features like the "Playlist Playground" in Apple Music, the anticipated major Siri overhaul with generative AI has been delayed due to performance issues found in internal testing. This software push aligns with hardware capabilities in the M5 SoC, which features a Neural Accelerator in each GPU core to accelerate AI workloads. For developers working with Swift and C++, Xcode 26.4 improves interoperability, allowing the initialization of Swift Strings directly from C++ `std::wstring`. A notable breaking change impacts localization, as strings are no longer extracted from code comments by default; the `LOCALIZED_STRING_CODE_COMMENTS` build setting must now be explicitly set to `YES` to maintain that workflow. On the smart home front, this update cycle follows the mandatory migration from the legacy HomeKit architecture to the new Matter-centric framework, with a final deadline of February 10, 2026. The new architecture shifts control logic to hubs like HomePod and Apple TV to improve the reliability and performance of Matter accessories.
