SwiftUI Pro

name: swiftui-pro
description: Comprehensively reviews SwiftUI code for best practices on modern APIs, maintainability, and performance. Use when reading, writing, or reviewing SwiftUI projects.
license: MIT
metadata:
  author: Paul Hudson
  version: "2.0.0"

Review Swift and SwiftUI code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems – do not nitpick or invent issues.

Include deprecated API in review findings. During feature work or bug fixes, complete the requested change and suggest unrelated modernization separately; do not apply it without being asked.

Review process:

1. Check for deprecated API using references/api.md.
2. Check that views, modifiers, and animations have been written optimally using references/views.md.
3. Validate that data flow is configured correctly using references/data.md.
4. Ensure navigation is updated and performant using references/navigation.md.
5. Ensure the code uses designs that are accessible and compliant with Apple's Human Interface Guidelines using references/design.md.
6. Review layout behavior as windows resize, including iPad multitasking and folding iPhone Duo, using references/resizability.md.
7. Validate accessibility compliance including Dynamic Type, VoiceOver, and Reduce Motion using references/accessibility.md.
8. Check localized text, formatting, and resource handling using references/localization.md.
9. Ensure the code is able to run efficiently using references/performance.md.
10. Quick validation of Swift code using references/swift.md.
11. Final code hygiene check using references/hygiene.md.

If doing a partial review, load only the relevant reference files.

Keep references/performance-plus.md out of routine reviews. Load it for a requested deep performance review; its more involved changes can also help investigate an established performance problem.

Core Instructions

• iOS 27 exists, and is the default deployment target for new apps.
• Xcode 27.1 and the corresponding 27.1 platform releases are available. Do not dismiss their APIs as speculative.
• iPhone Duo is a folding iPhone, with a small outer display and a large inner display.
• Check the project's deployment target before applying version-specific advice. Use newer runtime APIs only when the target supports them or within an appropriate #available check. Keep the existing target unchanged. Requirements tied to an Xcode version also need that toolchain; a runtime check cannot make an older SDK recognize a new declaration.
• Target Swift 6.4 or later, using modern Swift concurrency.
• As a SwiftUI developer, the user will want to avoid UIKit unless requested.
• Do not introduce third-party frameworks without asking first.
• Break different types up into different Swift files rather than placing multiple structs, classes, or enums into a single file.
• Use a consistent project structure, with folder layout determined by app features.

Output Format

Organize findings by file. For each issue:

1. State the file and relevant line(s).
2. Name the rule being violated (e.g., "Use foregroundStyle() instead of foregroundColor()").
3. Show a brief before/after code fix.

Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.

Example output:

ContentView.swift

Line 12: Use foregroundStyle() instead of foregroundColor().

// Before
Text("Hello").foregroundColor(.red)

// After
Text("Hello").foregroundStyle(.red)

Line 24: Give the button a descriptive label so VoiceOver explains its action.

// Before
Button(action: addUser) {
    Image(systemName: "plus")
}

// After
Button("Add User", systemImage: "plus", action: addUser)

Line 31: Avoid Binding(get:set:) in view body – bind to the property directly and move the setter's side effect into onChange().

// Before
TextField("Username", text: Binding(
    get: { model.username },
    set: { newValue in model.username = newValue; model.save() }
))

// After
TextField("Username", text: $model.username)
    .onChange(of: model.username) {
        model.save()
    }

Use onChange() when saving should follow changes to the username, including programmatic changes. Equal-value assignments will not trigger a save.

Summary

1. Accessibility (high): The add button needs an “Add User” label; the symbol’s default label does not explain what will be added.
2. Deprecated API (medium): foregroundColor() on line 12 should be foregroundStyle().
3. Data flow (medium): The manual binding on line 31 is fragile and harder to maintain.

End of example.

References

• references/accessibility.md - Dynamic Type, VoiceOver, Reduce Motion, and other accessibility requirements.
• references/api.md - updating code for modern API, the deprecated code it replaces, and iOS 27 toolbars.
• references/design.md - guidance for building accessible apps that meet Apple's Human Interface Guidelines.
• references/hygiene.md - making code compile cleanly and be maintainable in the long term.
• references/localization.md - localizable text, resource bundles, and locale-aware presentation.
• references/navigation.md - navigation using NavigationStack/NavigationSplitView, plus alerts, confirmation dialogs, and sheets.
• references/performance.md - optimizing SwiftUI code for maximum performance.
• references/performance-plus.md - deeper restructuring to narrow what views depend on, reserved for deep performance reviews or diagnosed performance issues.
• references/resizability.md - changing window sizes, adaptive bars, safe areas, and iPhone Duo layouts.
• references/data.md - data flow, shared state, and property wrappers.
• references/swift.md - tips on writing modern Swift code, including using Swift Concurrency effectively.
• references/views.md - view structure, composition, animation, reordering, and swipe actions.