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axiom-uikit

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Use when bridging UIKit and SwiftUI, modernizing UIKit apps (scene lifecycle, resizability), debugging Auto Layout, Combine, TextKit, PencilKit, or UIKit animations.

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How to use this skill

Bring this guide into your coding agent with a prompt tailored to the tool you use.

  1. Open your project in Codex.
  2. Copy the prompt below and paste it into your agent.
  3. Review the proposed files and risks before you approve installation.
Prompt to paste
I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/CharlesWiltgen/Axiom/blob/HEAD/.claude-plugin/plugins/axiom/skills/axiom-uikit/SKILL.md

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First, summarize what it does, its dependencies, license status if identifiable, and any risks. Show the exact files you propose to add under .agents/skills/axiom-uikit/. Do not write files or run scripts until I approve.

After I approve, install the complete skill folder, including required referenced files, into that project location. Verify it is discoverable, then tell me its actual invocation name and how to use it. Do not claim it is installed until you have verified it.

Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

UIKit & Bridging

You MUST use this skill for ANY UIKit bridging, Auto Layout, Combine, TextKit, or UIKit animation work.

Quick Reference

Symptom / TaskReference
UIViewRepresentable, UIViewControllerRepresentableSee skills/uikit-bridging.md
Embedding SwiftUI in UIKit (UIHostingController)See skills/uikit-bridging.md
Coordinator pattern, updateUIView lifecycleSee skills/uikit-bridging.md
"Unable to simultaneously satisfy constraints"See skills/auto-layout-debugging.md
Constraint conflicts, ambiguous layoutSee skills/auto-layout-debugging.md
Views not appearing, positioned incorrectlySee skills/auto-layout-debugging.md
CAAnimation completion handler not firingSee skills/uikit-animation-debugging.md
Spring physics wrong on device, duration mismatchSee skills/uikit-animation-debugging.md
Animation jank, CATransaction timingSee skills/uikit-animation-debugging.md
Combine publishers, AnyCancellable lifecycleSee skills/combine-patterns.md
@Published properties, Combine ↔ async/awaitSee skills/combine-patterns.md
When to use Combine vs async/awaitSee skills/combine-patterns.md
UIScene lifecycle required, resizable apps, size classes, tab sidebar OS27See skills/uikit-modernization.md
TextKit 2 architecture, NSTextLayoutManagerSee skills/textkit-ref.md
Writing Tools integration (iOS 26)See skills/textkit-ref.md
Viewport rendering surfaces, attachment reuse, collapsible text OS27See skills/textkit-ref.md
SwiftUI TextEditor, TextKit 1 migrationSee skills/textkit-ref.md
PencilKit canvas, PKToolPicker, drawing persistenceSee skills/pencilkit-paperkit.md
Apple Pencil Pro (squeeze, barrel roll, hover, haptics)See skills/pencilkit-paperkit.md
Handwriting recognition (PKStrokeRecognizer), stroke identity/slicing OS27See skills/pencilkit-paperkit-ref.md
PaperKit markup canvas (shapes, images, text + drawing)See skills/pencilkit-paperkit-ref.md
PaperKit programmatic markup model (subelements, adornments) OS27See skills/pencilkit-paperkit-ref.md

Decision Tree

digraph uikit {
    start [label="UIKit task" shape=ellipse];
    what [label="What do you need?" shape=diamond];

    start -> what;
    what -> "skills/uikit-bridging.md" [label="wrap UIKit in SwiftUI\nor SwiftUI in UIKit"];
    what -> "skills/auto-layout-debugging.md" [label="constraint errors,\nlayout issues"];
    what -> "skills/uikit-animation-debugging.md" [label="CAAnimation bugs,\nspring physics,\ncompletion handlers"];
    what -> "skills/combine-patterns.md" [label="publishers, sinks,\n@Published,\nasync/await bridge"];
    what -> "skills/textkit-ref.md" [label="text layout,\nWriting Tools,\nTextKit migration"];
    what -> "skills/pencilkit-paperkit.md" [label="drawing canvas,\nApple Pencil,\nPaperKit markup"];
    what -> "skills/uikit-modernization.md" [label="scene lifecycle (required 27),\nresizable apps,\nsize classes"];
}
  1. Scene-lifecycle migration, "app won't launch on 27", resizability, size classes, tab sidebar? → skills/uikit-modernization.md
  2. UIViewRepresentable / UIViewControllerRepresentable / UIHostingController? → skills/uikit-bridging.md
  3. "Unable to simultaneously satisfy constraints" / layout bugs? → skills/auto-layout-debugging.md
  4. CAAnimation completion missing / spring physics wrong / animation jank? → skills/uikit-animation-debugging.md
  5. Combine publishers / AnyCancellable / @Published / Combine ↔ async bridge? → skills/combine-patterns.md
  6. TextKit 2 / Writing Tools / TextEditor / TextKit 1 migration? → skills/textkit-ref.md
  7. PencilKit canvas / Apple Pencil / PaperKit markup? → skills/pencilkit-paperkit.md
  8. Pure SwiftUI view question (no UIKit bridging)? → /skill axiom-swiftui
  9. Design decisions, HIG, Liquid Glass, SF Symbols, typography? → /skill axiom-design
  10. Block retain cycles in UIKit callbacks? → See axiom-performance (skills/objc-block-retain-cycles.md)
  11. Memory leaks from Combine subscriptions? → Start with skills/combine-patterns.md, then axiom-performance if leak persists

Conflict Resolution

uikit vs swiftui: When working with UI code:

  • Use uikit when wrapping UIKit in SwiftUI or vice versa, or debugging UIKit-specific issues (Auto Layout, CAAnimation)
  • Use swiftui for pure SwiftUI views, navigation, layout, animations

uikit vs concurrency: When Combine interacts with async/await:

  • Use uikit (skills/combine-patterns.md) for bridging Combine pipelines with async/await
  • Use concurrency for pure async/await patterns, actors, Sendable

uikit vs performance: When animations or layout cause performance issues:

  1. Try uikit FIRST — Most animation jank is CATransaction timing or layer state, not a profiling issue
  2. Only use performance if animation logic is correct but rendering is slow

uikit vs axiom-data: When @Published properties relate to data persistence:

  • Use uikit for Combine publisher patterns and @Published lifecycle
  • Use axiom-data for SwiftData/Core Data model layer concerns

Anti-Rationalization

ThoughtReality
"I'll just use UIHostingController, it's simple"Hosting has sizing, lifecycle, and navigation edge cases. skills/uikit-bridging.md covers the gotchas.
"Auto Layout error is just a warning, I'll ignore it"Unsatisfied constraints cause unpredictable layout at runtime. Fix them now.
"I know how CAAnimation works"90% of CAAnimation bugs are CATransaction timing, not Core Animation. Check skills/uikit-animation-debugging.md.
"Combine is dead, just rewrite with async/await"Combine has no deprecation notice. Rewriting working pipelines wastes time. skills/combine-patterns.md covers when to migrate vs maintain.
"TextKit 1 still works fine"TextKit 1 misses Writing Tools integration and has known layout bugs Apple won't fix. See skills/textkit-ref.md.
"I'll store cancellables in a local variable"Local AnyCancellable deallocates immediately, killing the subscription.
"I'll archive the PKCanvasView to save the drawing"Archiving the view loses editability. Persist drawing.dataRepresentation(). See skills/pencilkit-paperkit.md.
"My tool picker won't show, the API must be broken"The canvas must becomeFirstResponder() after setVisible(_:forFirstResponder:). See skills/pencilkit-paperkit.md.

Example Invocations

User: "How do I wrap a UIKit view in SwiftUI?" → Read: skills/uikit-bridging.md

User: "I'm getting 'Unable to simultaneously satisfy constraints'" → Read: skills/auto-layout-debugging.md

User: "My CAAnimation completion handler never fires" → Read: skills/uikit-animation-debugging.md

User: "Should I use Combine or async/await for this?" → Read: skills/combine-patterns.md

User: "How do I integrate Writing Tools with my text editor?" → Read: skills/textkit-ref.md

User: "How do I add an Apple Pencil drawing canvas with the tool picker?" → Read: skills/pencilkit-paperkit.md

User: "How do I add a PaperKit markup canvas with shapes and text?" → Read: skills/pencilkit-paperkit-ref.md

User: "My SwiftUI view has a memory leak from a Combine subscription" → Read: skills/combine-patterns.md

User: "How do I embed SwiftUI in my UIKit app?" → Read: skills/uikit-bridging.md