browserenginekit

BrowserEngineKit is Apple's framework for building web browsers that ship their own non-WebKit rendering engine on iOS and iPadOS, and this skill covers the full setup: eligibility, entitlements, process architecture, capabilities, and system integration. Alternative engines are gated to supported regions and Apple-approved entitlement profiles: the EU on iOS 17.4+/iPadOS 18+, and Japan starting iOS 26.2 with additional Pointer Authentication Code and Memory Integrity Enforcement requirements, while development and testing can happen anywhere. Device eligibility is checked at runtime with BEAvailability.isEligible(for: .webBrowser) from the companion BrowserKit framework rather than hard-coded region logic. A browser is split across four processes: a host app for UI and coordination, plus web content, networking, and rendering extensions that communicate over XPC. The host launches and manages every extension, brokers anonymous XPC endpoints between them during a defined bootstrap sequence, and follows least privilege so the web content extension handles untrusted data without direct OS access. Host process classes WebContentProcess, NetworkingProcess, and RenderingProcess expose async initializers with interruption handlers, makeLibXPCConnection() for messaging, and invalidate() to stop. The skill enumerates the required host entitlements (com.apple.developer.web-browser and web-browser-engine.host), per-extension entitlements for web content, networking, and rendering, and optional ones for JIT compilation, extended virtual addressing, and memory attribution transfer. It also documents the separate model for non-browser apps that embed an engine for in-app browsing, which uses embedded-web-browser-engine entitlements, arm64 only, and cannot use JIT or browser extensions. Availability anchors are called out throughout: process APIs at 17.4+, BEDownloadMonitor at 18.2+, the .revision2 restricted sandbox at 26+, and CoreML rendering at 26.2+. Examples target Swift 6.3 and current Apple SDKs, rounded out with a review checklist and common-mistakes guidance.