# Xcode 16.4 Release Notes Update your apps to use new features, and test your apps against API changes. ## Overview Xcode 16.4 includes SDKs for iOS 18.5, iPadOS 18.5, tvOS 18.5, watchOS 11.5, macOS Sequoia 15.5, and visionOS 2.5. The Xcode 16.4 release supports on-device debugging in iOS 15 and later, tvOS 15 and later, watchOS 7 and later, and visionOS. Xcode 16.4 requires a Mac running macOS Sequoia 15.3 through macOS Tahoe 26.1. ### General #### Resolved Issues - Fixed: Users may see excessive CPU utilization from diskimagesiod which reduces simulator performance, increasing boot time, process launch times, and test execution times. (146716769) (FB16818022) ### Apple Clang Compiler #### Resolved Issues - Fixed: The base template for `std::char_traits` is restored after being removed in Xcode 16.3; it is still deprecated and is going to be removed in a future release. Restoring the base template allows code that attempts to instantiate `char_traits` with types that are not provided by the Standard (for example, `std::basic_string` and similar) to still compile, giving it more time to transition. (149025504) ### Device #### New Features - The command `devicectl diagnose` now obtains a sysdiagnose from your Mac and all available devices by default. (104845318) ### Instruments #### Resolved Issues - Fixed: Improved error handling for the Processor Trace Instrument when targeting binary not signed with get-task-allow entitlement. (139032322) ### Simulator #### Resolved Issues - Fixed: NSURLSession was always timing out and failing in iOS 18.3 simulator runtimes. (147849952) (FB17006003) ### Source Editor #### Resolved Issues - Fixed: Some C++ headers were experiencing crashes in syntax highlighting and Quick Help. (148020379) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)