UIKit & Bridging

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

Can't launch Axiom agents? Where this router sends you to an agent, follow its procedure inline. Over MCP, axiom_get_agent returns it; elsewhere, read its file below, which needs only file search and read.

Available here: skills/resize-auditor.md.

For any other agent, over MCP axiom_get_agent returns it too; run its xclog, xcsym and xcprof steps with the axiom_xclog_*, axiom_xcsym_* and axiom_xcprof_* tools. Elsewhere, search Axiom's skills for skills/<agent>.md; if there is none, do that work yourself with this suite's skills, using any Axiom tool on your PATH.

Quick Reference

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/adaptive-layout.md" [label="build adaptive layout\n(guides, constraint sets,\ncompositional)"];
    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"];
}

0. Scene-lifecycle migration, "app won't launch on 27", resizability, size classes, tab sidebar? → skills/uikit-modernization.md 0b. App misbehaves in iPhone Mirroring (gestures dead, Face ID blocked, layout stuck portrait)? → skills/uikit-modernization.md 0c. iPhone Duo / foldable iPhone (vertical bars, the fold, outer-display window requests)? → axiom-swiftui (skills/iphone-duo.md)
1. UIViewRepresentable / UIViewControllerRepresentable / UIHostingController? → skills/uikit-bridging.md
2. "Unable to simultaneously satisfy constraints" / layout bugs? → skills/auto-layout-debugging.md 2b. Building a layout that adapts (layout guides, size-class constraint sets, compositional column math, self-sizing cells)? → skills/adaptive-layout.md
3. CAAnimation completion missing / spring physics wrong / animation jank? → skills/uikit-animation-debugging.md
4. Combine publishers / AnyCancellable / @Published / Combine ↔ async bridge? → skills/combine-patterns.md
5. TextKit 2 / Writing Tools / TextEditor / TextKit 1 migration? → skills/textkit-ref.md
6. PencilKit canvas / Apple Pencil / PaperKit markup? → skills/pencilkit-paperkit.md
7. Pure SwiftUI view question (no UIKit bridging)? → /skill axiom-swiftui
8. Design decisions, HIG, Liquid Glass, SF Symbols, typography? → /skill axiom-design
9. Block retain cycles in UIKit callbacks? → See axiom-performance (skills/objc-block-retain-cycles.md)
10. 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

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

User: "Audit my app for screen resizing support" → Launch resize-auditor agent (or /axiom:audit resize)

User: "My custom pinch gesture stops working when the app runs in iPhone Mirroring" → Read: skills/uikit-modernization.md

User: "How do I vary my collection view's column count with the window width?" → Read: skills/adaptive-layout.md