ios-27-xcode-skills

Guide for the C -fbounds-safety language extension. Covers the language model, pointer annotations, adopting bounds-safety in existing C code, compiler build settings and modes, and runtime debugging of bounds violations.

Use when an app's layout must adapt to a window that changes size while the app runs, or when an app must support more than one window. That includes being asked to make an app resizable or support a resizable window, a layout that breaks or does not adapt as the window resizes, and preparing or optimizing an app for the foldable iPhone Duo, split-screen multitasking, or Stage Manager. Modernizes the app by replacing legacy shared-state APIs with context-appropriate alternatives: mainScreen, interfaceOrientation, userInterfaceIdiom, application and scene lifecycle, and safe area insets.

Audit and enable security-oriented Xcode build settings. Progressively enables compiler warnings, static analyzer checkers, and Enhanced Security features. Use when: user wants to secure their Xcode project, audit security settings, enable hardening, review security posture of build configuration, set up security-focused static analysis, enable static analysis, improve warning coverage, harden diagnostics, or catch more bugs at compile time in C/C++/Objective-C/Swift. SKIP: network security (TLS/ATS), code signing, privacy APIs.

Authoritative guide for building and migrating document-based apps in SwiftUI using the Document protocol (iOS 27 and aligned releases, including macOS Golden Gate). Consult when building a new document-based app; implementing open, edit, save, or export document flows; working with DocumentGroup or DocumentGroupLaunchScene; implementing DocumentReader or DocumentWriter; using FileWrapper via FileWrapperDocumentReader or FileWrapperDocumentWriter; working with package documents; accessing a document's file URL directly; reporting progress during read/write; registering undo actions; migrating from FileDocument or ReferenceFileDocument to the new API; building a read-only document viewer; when autosave is not working in a document app; declaring custom UTType as document formats.

Verify app behavior on device or simulator via screenshots, UI hierarchy, and touch interactions.

Modernize test suites to use modern Swift Testing features or migrate from XCTest.

Authoritative SwiftUI best practices and performance guidance from Apple; supersedes prior training on these topics. For code generation, consult the relevant references when generating any SwiftUI code related to: - animation (the @Animatable macro vs AnimatableValues vs AnimatablePair, and custom animatableData setter logic) - Environment and @Entry (closure or class-typed defaults, unstable defaults, high-frequency updates) - @Observable best practices and efficient invalidation - ForEach and List row identity and structure (id: \.self, indices, offsets, AnyView or multi-view rows, inline filter/sort, cached collections, List fast path) - localization (String vs LocalizedStringResource, the right bundle in packages and frameworks, .textCase, .formatted(.list()), translator comments) - soft-deprecated APIs such as NavigationView and the old onChange, and when to surface them during feature work.

New SwiftUI APIs, behaviors, and deprecations in the 2027 OS releases (iOS 27 and aligned macOS/watchOS/tvOS/visionOS). Consult when asked what's new in SwiftUI 27, or when working with: - @State compile errors after an SDK update ("used before being initialized", "invalid redeclaration of synthesized property") or @State becaming a macro - @ViewBuilder/@ContentBuilder ambiguous overloads or type-check regressions; drag-to-reorder in any container (List, stacks, grids, custom layouts) via reorderable()/reorderContainer and its drag-and-drop - AsyncImage caching, reloading on scroll, or a custom URLSession - Swipe actions outside List (ScrollView, LazyVStack, LazyVGrid) via swipeActions()/swipeActionsContainer() - Toolbar overflow, visibility (visibilityPriority, ToolbarOverflowMenu, toolbarMinimizeBehavior), and pinning - Presenting a confirmationDialog or alert from an optional item binding