Claude Skills
The open format is called Agent Skills and works in Claude Code, Codex, Cursor and other agents — most people know it as Claude Skills.
Every Agent Skill we could find on GitHub, deduplicated by content. 79 437 files from 1 744 authors, of which 61 785 are unique — the rest is the same skill repackaged into someone else's repository. For each one: what it weighs in tokens, whether it ships runnable scripts, and which MCP servers it needs.
RealityKit API reference — Entity, Component, System, RealityView, Model3D, anchor types, material system, physics, collision, animation, audio, accessibility
Use when building 3D content, AR experiences, or spatial computing with RealityKit. Covers ECS architecture, SwiftUI integration, RealityView, AR anchors, materials, physics, interaction, multiplayer, performance.
Use when migrating from Realm to SwiftData - comprehensive migration guide covering pattern equivalents, threading model conversion, schema migration strategies, CloudKit sync transition, and real-world scenarios
SceneKit → RealityKit concept mapping, complete API cross-reference for migration, scene graph API, materials, lighting, camera, physics, animation, constraints
Use when working with SceneKit 3D scenes, migrating SceneKit to RealityKit, or maintaining legacy SceneKit code. Covers scene graph, materials, physics, animation, SwiftUI bridge, migration decision tree.
Use when you need complete SF Symbols API reference including every rendering mode, symbol effect, configuration option, UIKit equivalent, and platform availability - comprehensive code examples for iOS 17 through iOS 26
Use when implementing SF Symbols rendering modes, symbol effects, animations, custom symbols, or troubleshooting symbol appearance - covers the full symbol effects system from iOS 17 through SF Symbols 7 Draw animations in iOS 26
Use when preparing ANY app for submission, handling App Store rejections, writing appeals, or managing App Store Connect. Covers submission checklists, rejection troubleshooting, metadata requirements, privacy manifests, age ratings, export compliance.
Use when physics contacts don't fire, objects tunnel through walls, frame rate drops, touches don't register, memory spikes, coordinate confusion, or scene transition crashes
SpriteKit API reference — all node types, physics body creation, action catalog, texture atlases, constraints, scene setup, particles, SKRenderer
Use when building SpriteKit games, implementing physics, actions, scene management, or debugging game performance. Covers scene graph, physics engine, actions system, game loop, rendering optimization.
Use when migrating from SwiftData to SQLiteData — decision guide, pattern equivalents, code examples, CloudKit sharing (SwiftData can't), performance benchmarks, gradual migration strategy
SQLiteData advanced patterns, @Selection column groups, single-table inheritance, recursive CTEs, database views, custom aggregates, TableAlias self-joins, JSON/string aggregation
Use when working with SQLiteData @Table models, CRUD operations, query patterns, CloudKit SyncEngine setup, or batch imports. Covers model definitions, @FetchAll/@FetchOne, upsert patterns, database setup with Dependencies.
Use when debugging 'files disappeared', 'data missing after restart', 'backup too large', 'can't save file', 'file not found', 'storage full error', 'file inaccessible when locked' - systematic local file storage diagnostics
Use when asking about 'purge files', 'storage pressure', 'disk space iOS', 'isExcludedFromBackup', 'URL resource values', 'volumeAvailableCapacity', 'low storage', 'file purging priority', 'cache management' - comprehensive reference for iOS storage management and URL resource value APIs
Use when asking 'where should I store this data', 'should I use SwiftData or files', 'CloudKit vs iCloud Drive', 'Documents vs Caches', 'local or cloud storage', 'how do I sync data', 'where do app files go' - comprehensive decision framework for all iOS storage options
Reference — Complete StoreKit 2 API guide covering Product, Transaction, AppTransaction, RenewalInfo, SubscriptionStatus, StoreKit Views, purchase options, server APIs, and all iOS 18.4 enhancements with WWDC 2025 code examples
Swift concurrency API reference — actors, Sendable, Task/TaskGroup, AsyncStream, continuations, isolation patterns, DispatchQueue-to-actor migration with gotcha tables
Use when you see 'actor-isolated', 'Sendable', 'data race', '@MainActor' errors, or when asking 'why is this not thread safe', 'how do I use async/await', 'what is @MainActor for', 'my app is crashing with concurrency errors', 'how do I fix data races' - Swift 6 strict concurrency patterns with actor isolation and async/await
Use when reviewing or generating Swift code for modern idiom correctness — catches outdated APIs, pre-Swift 5.5 patterns, and Foundation legacy usage that Claude defaults to
Use when optimizing Swift code performance, reducing memory usage, improving runtime efficiency, dealing with COW, ARC overhead, generics specialization, or collection optimization
Use when writing unit tests, adopting Swift Testing framework, making tests run faster without simulator, architecting code for testability, testing async code reliably, or migrating from XCTest - covers @Test/@Suite macros, #expect/#require, parameterized tests, traits, tags, parallel execution, host-less testing
Use when SwiftData migrations crash, fail to preserve relationships, lose data, or work in simulator but fail on device - systematic diagnostics for schema version mismatches, relationship errors, and migration testing gaps
Use when creating SwiftData custom schema migrations with VersionedSchema and SchemaMigrationPlan - property type changes, relationship preservation (one-to-many, many-to-many), the willMigrate/didMigrate limitation, two-stage migration patterns, and testing migrations on real devices
Use when working with SwiftData - @Model definitions, @Query in SwiftUI, @Relationship macros, ModelContext patterns, CloudKit integration, iOS 26+ features, and Swift 6 concurrency with @MainActor — Apple's native persistence framework
Use when implementing iOS 26 SwiftUI features - covers Liquid Glass design system, performance improvements, @Animatable macro, 3D spatial layout, scene bridging, WebView/WebPage, AttributedString rich text editing, drag and drop enhancements, and visionOS integration for iOS 26+
Use when implementing SwiftUI animations, understanding VectorArithmetic, using @Animatable macro, zoom transitions, UIKit/AppKit animation bridging, choosing between spring and timing curve animations, or debugging animation behavior - comprehensive animation reference from iOS 13 through iOS 26
Use when separating logic from SwiftUI views, choosing architecture patterns, refactoring view files, or asking 'where should this code go', 'how do I organize my SwiftUI app', 'MVVM vs TCA vs vanilla SwiftUI', 'how do I make SwiftUI testable' - comprehensive architecture patterns with refactoring workflows for iOS 26+
Reference — SwiftUI stacks, grids, outlines, and scroll enhancements through iOS 26
Use when SwiftUI view debugging requires systematic investigation - view updates not working after basic troubleshooting, intermittent UI issues, complex state dependencies, or when Self._printChanges() shows unexpected update patterns - systematic diagnostic workflows with Instruments integration
Use when debugging SwiftUI view updates, preview crashes, or layout issues - diagnostic decision trees to identify root causes quickly and avoid misdiagnosis under pressure
Use when implementing SwiftUI gestures (tap, drag, long press, magnification, rotation), composing gestures, managing gesture state, or debugging gesture conflicts - comprehensive patterns for gesture recognition, composition, accessibility, and cross-platform support
Reference — Complete SwiftUI adaptive layout API guide covering ViewThatFits, AnyLayout, Layout protocol, onGeometryChange, GeometryReader, size classes, and iOS 26 window APIs
Use when layouts need to adapt to different screen sizes, iPad multitasking, or iOS 26 free-form windows — decision trees for ViewThatFits vs AnyLayout vs onGeometryChange, size class limitations, and anti-patterns preventing device-based layout mistakes
Use when debugging navigation not responding, unexpected pops, deep links showing wrong screen, state lost on tab switch or background, crashes in navigationDestination, or any SwiftUI navigation failure - systematic diagnostics with production crisis defense
Reference — Comprehensive SwiftUI navigation guide covering NavigationStack (iOS 16+), NavigationSplitView (iOS 16+), NavigationPath, deep linking, state restoration, Tab+Navigation integration (iOS 18+), Liquid Glass navigation (iOS 26+), and coordinator patterns
Use when implementing navigation patterns, choosing between NavigationStack and NavigationSplitView, handling deep links, adopting coordinator patterns, or requesting code review of navigation implementation - prevents navigation state corruption, deep link failures, and state restoration bugs for iOS 18+
Use when UI is slow, scrolling lags, animations stutter, or when asking 'why is my SwiftUI view slow', 'how do I optimize List performance', 'my app drops frames', 'view body is called too often', 'List is laggy' - SwiftUI performance optimization with Instruments 26 and WWDC 2025 patterns
Use when implementing SwiftUI search — .searchable, isSearching, search suggestions, scopes, tokens, programmatic search control (iOS 15-18). For iOS 26 search refinements (bottom-aligned, minimized toolbar, search tab role), see swiftui-26-ref.
Use when needing thread-safe primitives for performance-critical code. Covers Mutex (iOS 18+), OSAllocatedUnfairLock (iOS 16+), Atomic types, when to use locks vs actors, deadlock prevention with Swift Concurrency.
Use when ANY beta tester reports a crash, ANY crash appears in Organizer or App Store Connect, crash logs need symbolication, app was killed without crash report, or you need to triage TestFlight feedback
Use when testing async code with Swift Testing. Covers confirmation for callbacks, @MainActor tests, async/await patterns, timeout control, XCTest migration, parallel test execution.
TextKit 2 complete reference (architecture, migration, Writing Tools, SwiftUI TextEditor) through iOS 26
Timer, DispatchSourceTimer, Combine Timer.publish, AsyncTimerSequence, Task.sleep API reference with lifecycle diagrams, RunLoop modes, and platform availability
Use when implementing timers, debugging timer crashes (EXC_BAD_INSTRUCTION), Timer stops during scrolling, or choosing between Timer/DispatchSourceTimer/Combine/async timer APIs
Use when implementing drag and drop, copy/paste, ShareLink, or ANY content sharing between apps or views - covers Transferable protocol, TransferRepresentation types, UTType declarations, SwiftUI surfaces, and NSItemProvider bridging
Use when building ANY tvOS app - covers Focus Engine, Siri Remote input, storage constraints (no Document directory), no WebView, TVUIKit, TextField workarounds, AVPlayer tuning, Menu button state machines, and tvOS-specific gotchas that catch iOS developers
Apple platform typography reference (San Francisco fonts, text styles, Dynamic Type, tracking, leading, internationalization) through iOS 26
Use when setting up UI test recording in Xcode 26, enhancing recorded tests for stability, or configuring test plans for multi-configuration replay. Based on WWDC 2025-344 "Record, replay, and review".
Use when writing UI tests, recording interactions, tests have race conditions, timing dependencies, inconsistent pass/fail behavior, or XCTest UI tests are flaky - covers Recording UI Automation (WWDC 2025), condition-based waiting, network conditioning, multi-factor testing, crash debugging, and accessibility-first testing patterns
Use when CAAnimation completion handler doesn't fire, spring physics look wrong on device, animation duration mismatches actual time, gesture + animation interaction causes jank, or timing differs between simulator and real hardware - systematic CAAnimation diagnosis with CATransaction patterns, frame rate awareness, and device-specific behavior
Use when wrapping UIKit views/controllers in SwiftUI, embedding SwiftUI in UIKit, or debugging UIKit-SwiftUI interop issues. Covers UIViewRepresentable, UIViewControllerRepresentable, UIHostingController, UIHostingConfiguration, coordinators, lifecycle, state binding, memory management.
Use when starting any iOS/Swift conversation - establishes how to find and use Axiom skills, requiring Skill tool invocation before ANY response including clarifying questions
Use when auditing user journeys, checking for UX dead ends, dismiss traps, buried CTAs, missing empty/loading/error states, or broken data paths in iOS apps (SwiftUI and UIKit).
subject not detected, hand pose missing landmarks, low confidence observations, Vision performance, coordinate conversion, VisionKit errors, observation nil, text not recognized, barcode not detected, DataScannerViewController not working, document scan issues
Use when needing Vision framework API details for hand/body pose, segmentation, text recognition, barcode detection, document scanning, or Visual Intelligence integration. Covers VNRequest types, coordinate conversion, DataScannerViewController, RecognizeDocumentsRequest, SemanticContentDescriptor, IntentValueQuery.
subject segmentation, VNGenerateForegroundInstanceMaskRequest, isolate object from hand, VisionKit subject lifting, image foreground detection, instance masks, class-agnostic segmentation, VNRecognizeTextRequest, OCR, VNDetectBarcodesRequest, DataScannerViewController, document scanning, RecognizeDocumentsRequest
Use when capturing iOS simulator console output, diagnosing runtime crashes, viewing print/os_log output, or needing structured app logs for analysis. Reference for xclog CLI covering launch, attach, list modes with JSON output.
Use when encountering BUILD FAILED, test crashes, simulator hangs, stale builds, zombie xcodebuild processes, "Unable to boot simulator", "No such module" after SPM changes, or mysterious test failures despite no code changes - systematic environment-first diagnostics for iOS/macOS projects
Claude Skills — questions
Answers built from the skills we actually parsed.