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quicklook

Preview documents, images, audio, and 3D USDZ files with QLPreviewController and SwiftUI .quickLookPreview, and generate asynchronous thumbnails using QLThumbnailGenerator in iOS apps.

Quality

82%

Does it follow best practices?

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SKILL.md
Quality
Evals
Security

Quality

Content

86%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

The body is an efficient, highly actionable QuickLook reference: complete executable Swift examples for each API, a genuinely useful Common Mistakes section, and a review checklist for verification. Advanced patterns are correctly offloaded to a real, well-described one-level-deep reference file, with only minor token overhead from the redundant table of contents.

DimensionReasoningScore

Conciseness

Each section opens with a single earning sentence ("For multi-file carousels, custom navigation transitions, or fine-grained preview control, use `QLPreviewController`") and the bulk is complete code, matching anchor 4 (efficient, minor trimmable instances). Not 5 because the redundant 'Contents' table of contents and a few restating sentences (the intro repeats the description) could be trimmed.

4 / 5

Actionability

Four complete, copy-paste-ready Swift examples ("DocumentRowView" with `.quickLookPreview($previewURL)`, "DocumentPreviewCoordinator" with full `QLPreviewControllerDataSource` conformance, the "ThumbnailLoader" actor with `NSCache` caching, and "PreviewableDocument") plus a concrete Common Mistakes section with fixes ("always pass environment `@Environment(\.displayScale)`"). This matches anchor 5: fully executable examples covering the common cases.

5 / 5

Workflow Clarity

This is a per-use-case patterns skill, not a multi-step pipeline; selection guidance ("For multi-item carousels... use `QLPreviewController`") and a validation-style "Review Checklist" ("Are target files downloaded locally before passing to QuickLook?") provide most checkpoints, matching anchor 4. Not 5 because there are no explicit feedback loops, and not below 4 since no destructive or batch operations are involved and the checklist supplies the verification steps.

4 / 5

Progressive Disclosure

The body is a clear, well-navigated overview (contents list, per-topic sections, ~150 lines), and advanced material is split into a single well-signaled one-level-deep reference — "[QuickLook Patterns](references/quicklook-patterns.md) — SwiftUI custom preview sheets, zoom transitions, and thumbnail caching" — which exists in the bundle and matches its description. This matches anchor 5: appropriate split, clear navigation, references one level deep.

5 / 5

Total

18

/

20

Passed

Description

70%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

The description is specific, technical, and highly distinguishable, naming concrete APIs, file types, and actions. Its main weakness is the absence of any explicit 'when to use' trigger clause, which caps completeness at 3 and leaves invocation guidance entirely implicit.

Suggestions

Append a trigger clause such as 'Use when previewing local files in an iOS/iPadOS app, generating document thumbnails, or when the user mentions QLPreviewController, .quickLookPreview, QLThumbnailGenerator, or USDZ previews.'

Mention common user phrasings like 'file preview' or 'Quick Look' to broaden natural trigger-term coverage beyond the API names.

Optionally note secondary capabilities (multi-file preview carousels, custom preview titles) to close the specificity gap.

DimensionReasoningScore

Specificity

Quotes concrete actions — "Preview documents, images, audio, and 3D USDZ files" and "generate asynchronous thumbnails" — each tied to named frameworks ("QLPreviewController", "SwiftUI .quickLookPreview", "QLThumbnailGenerator"). This matches anchor 4 (several specific actions, minor gaps) rather than 5, since coverage stops at two core actions and omits secondary capabilities (multi-file carousels, custom preview titles).

4 / 5

Completeness

The 'what' is clear ("Preview documents... and generate asynchronous thumbnails... in iOS apps"), but there is no 'when' — no "Use when..." clause or equivalent trigger guidance anywhere in the description. Per the rubric guideline, a missing 'Use when...' clause caps completeness at 3 (anchor 3: clear 'what', 'when' missing); it is not 4 because "in iOS apps" is a platform scope, not explicit trigger guidance.

3 / 5

Trigger Term Quality

Natural terms users would say include "Preview documents", "images", "audio", "3D USDZ files", "thumbnails", and "iOS apps" — good keyword coverage matching anchor 4. Not anchor 5 because common variations like "file preview", "PDF preview", "Quick Look", or a phrasing like "generate/generate file thumbnails" as a distinct natural phrase are thin.

4 / 5

Distinctiveness Conflict Risk

Framework names ("QLPreviewController", "QLThumbnailGenerator", "SwiftUI .quickLookPreview") and "3D USDZ files" carve out a clear niche with distinct triggers and minimal conflict risk with other skills, exactly matching anchor 5. It is not lower because nothing in the description is generic enough to collide with unrelated skills.

5 / 5

Total

16

/

20

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository

thienqo/ios-skills

Path

skills/quicklook/SKILL.md

Reviewed

Table of Contents

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