iOS Marketing Capture

iOS Marketing Capture

Overview

Automate reproducible marketing screenshot capture for a SwiftUI iOS app across multiple locales, with two parallel output streams:

1. Full-screen captures — every marketing-relevant screen, with deterministic seeded data, real status bar / safe-area chrome
2. Element captures — isolated renders of specific components (cards, widgets, charts) at any scale, with natural background inside rounded corners and transparency outside

This skill is the capture step. If the user also wants Apple-style marketing pages composited around the shots (device mockups, headlines, gradients), combine with the app-store-screenshots skill as a post-processing step.

Core Approach

In-app capture mode, not XCUITest. This is a hard decision that trades off against Fastlane snapshot / XCUITest conventions, and it wins for almost every real project.

Why in-app over XCUITest:

• No new test target. Adding a UI test target to an existing Xcode project is fragile pbxproj surgery. Many projects have zero test targets and no xcodegen — adding one by hand is error-prone.
• Faster iteration. A UI test takes 30s+ to launch per run. In-app capture is just a relaunch of the installed binary.
• No xcodebuild test. The whole flow is xcodebuild build once, then simctl launch per locale. No test-bundle overhead.
• Access to real app state. You can call ViewModels, SwiftData, ImageRenderer, and UIWindow.drawHierarchy directly. XCUITest can only tap and read accessibility elements.
• Element renders need in-process anyway. ImageRenderer on widget views or isolated components must run inside the app process — there's no XCUITest equivalent.

How it works:

1. A DEBUG-only MarketingCapture.swift file lives in the main app target
2. When launched with -MarketingCapture 1, the app seeds data, then a coordinator walks a list of CaptureSteps — each step navigates, waits for settle, snapshots, and cleans up
3. PNGs are written to the app's sandbox Documents/marketing/<locale>/ directory
4. A shell script builds once, installs, then loops locales by relaunching with -AppleLanguages (xx) -AppleLocale xx, pulling files out via simctl get_app_container

Process

Work through these steps in order. Do not skip ahead.

Step 1: Gather requirements

Ask the user these questions one at a time (do not batch them — each answer can invalidate later questions):

1. Screens to capture — "Which screens do you want? Give me the navigation path or the tab name for each." Get a concrete list, not "the main flows".
2. Isolated elements — "Any components you want rendered independently with transparent backgrounds? (carousel cards, widgets, hero tiles, charts, etc.)"
3. Locales — "Which locales? (a) all locales in your Localizable.xcstrings, (b) an App Store subset I'll specify, or (c) let me give you an explicit list." If (a), grep the .xcstrings file for locale codes:

   python3 -c "import json; d=json.load(open('<path>/Localizable.xcstrings')); langs=set(); [langs.update(v.get('localizations',{}).keys()) for v in d['strings'].values()]; print(sorted(langs))"

4. Device — "Which simulator? (6.1" iPhone 17 recommended for iOS 26 design features)" — verify the device is available via xcrun simctl list devices available.
5. Appearance — "Light only, dark only, or both?"
6. Seed data — "How is demo data populated today? (a) fresh install seeds it automatically, (b) there's a debug 'Load Demo Data' button, (c) you add it manually, (d) no demo data exists yet." Then: "Is the existing data exhaustive enough that every screen you listed looks populated for marketing? Audit it with the user."

Step 2: Exploration

Before writing any code, explore the codebase enough to answer:

• Does the project use Xcode synchronized folder groups (Xcode 16+, PBXFileSystemSynchronizedRootGroup)? If yes, new files auto-include in their target — no pbxproj edits needed. Check with grep -c PBXFileSystemSynchronized <proj>.xcodeproj/project.pbxproj.
• What is the root navigation pattern?
  • TabView(selection:) — most common. You need: the @State selectedTab binding, tab indices, and which tabs have nested NavigationStack.
  • NavigationStack (single stack with a router) — you need: the path binding or router object, plus the set of NavigationLink(value:) / .navigationDestination types.
  • NavigationSplitView — you need: the sidebar selection binding, detail column's navigation state.
  • Custom coordinator / UIKit host — you need: the coordinator's navigate(to:) method or equivalent.
• How are deep links routed? Find the onOpenURL handler and the enum/switch that maps URLs to navigation state.
• Where are demo data seeders defined? Trace the code path from the debug button (if any) to the function that actually writes to ModelContext. If no seeder exists, see "Creating a demo data seeder" below.
• Do widgets live in a separate target? Are the widget view files and entry types in the main app target too? (Almost certainly no — they need to be added if you want to render them via ImageRenderer.)
• Does the app use Live Activities / ActivityKit? If yes, flag this as a known gotcha (see below).
• Does the app use SwiftData + CloudKit sync (cloudKitDatabase: .automatic)? If yes, flag as a known gotcha.
• Does any view need to be captured in a non-default state? (e.g. a timer mid-countdown, a form partially filled, a chart with specific values). If yes, each needs a static var priming mechanism (see "Priming view state" below).

Step 3: Present design to user

Before writing code, summarize your plan in this structure. Get explicit approval before proceeding:

1. Architecture (in-app capture mode, single file, DEBUG-gated)
2. File list (exact paths you'll create / modify)
3. Screen-by-screen capture plan (how each screen is reached — tab index, navigation path, sheet trigger)
4. Capture ordering rationale (which screens must come before others — see gotcha #5)
5. Element rendering approach (which components, how they'll be wrapped)
6. Output layout (folder structure, naming convention)
7. Known gotchas relevant to this project (flagged from Step 2)
8. Primed states needed (which views, what static vars)

Step 4: Implement

Use the templates in templates/ as starting points. They are reference patterns, not copy-paste scaffolding — every project has different navigation, models, and views. The templates show the building blocks; you compose them for the target app.

Key files to produce:

• <AppName>/Debug/MarketingCapture.swift — the whole capture system, DEBUG-only. Contains:
  • MarketingCapture enum (launch arg parsing, output helpers, window snapshot, priming vars)
  • MarketingCaptureCoordinator class (walks [CaptureStep] and snapshots each)
  • MarketingElementHarness enum (ImageRenderer renders of cards, widgets, charts)
• <AppName>/ContentView.swift (or wherever the root view lives) — DEBUG hook that seeds data and runs the coordinator.
• Any views that need primed states — DEBUG-gated .onAppear hooks and .onReceive dismiss listeners.
• scripts/capture-marketing.sh — build + install + per-locale loop.
• .gitignore — add marketing/.

Step 5: Verify iteratively

Do not hand the script to the user and wait. Run it yourself against a simulator and verify at least one locale before declaring done. Read the output PNGs with the Read tool to visually verify each screen shows what you expect. Common runtime issues are listed in "Known Gotchas" below.

When you find an issue, fix it, rerun the whole script (not just the failing locale — fixes can regress earlier locales), and re-verify visually.

Architecture: Step-Based Capture

The coordinator drives capture by walking a list of CaptureStep values. Each step is self-contained: it knows how to navigate to its screen, how long to wait, and how to clean up afterward.

struct CaptureStep {
    let name: String                        // output filename, e.g. "01-home"
    let navigate: @MainActor () -> Void     // put the app in the right state
    let settle: Duration                    // wait for animations/loads
    let cleanup: (@MainActor () -> Void)?   // tear down before next step
}

The coordinator is a simple loop:

for step in steps {
    step.navigate()
    try? await Task.sleep(for: step.settle)
    if let image = MarketingCapture.snapshotKeyWindow() {
        MarketingCapture.writePNG(image, name: step.name)
    }
    step.cleanup?()
    try? await Task.sleep(for: .milliseconds(400))  // cleanup animation
}

Building steps for different navigation patterns

TabView app (most common):

// Simple tab switch — just set the index
CaptureStep(name: "01-home", navigate: { setTab(0) }, settle: .milliseconds(1800), cleanup: nil)

// Tab + presented sheet
CaptureStep(
    name: "05-timer-setup",
    navigate: {
        setTab(3)
        pendingBrewRecipe = someRecipe
    },
    settle: .milliseconds(2000),
    cleanup: {
        NotificationCenter.default.post(name: MarketingCapture.dismissSheetNotification, object: nil)
        pendingBrewRecipe = nil
    }
)

NavigationStack + router app:

// Push a route onto the stack
CaptureStep(
    name: "02-detail",
    navigate: { router.push(.itemDetail(item)) },
    settle: .milliseconds(1800),
    cleanup: { router.popToRoot() }
)

NavigationSplitView app:

// Select sidebar item, then detail
CaptureStep(
    name: "03-detail",
    navigate: {
        sidebarSelection = .recipes
        detailSelection = recipes.first
    },
    settle: .milliseconds(1800),
    cleanup: { detailSelection = nil }
)

Ordering: the stacking rule

Capture any screen that needs a "clean" navigation state BEFORE screens that push onto the same stack. Nested NavigationPath / @State inside child views can't be popped from the coordinator. So:

Good:  Shelf (clean list) → Coffee Detail (pushes onto shelf's stack)
Bad:   Coffee Detail → Shelf (stack still has detail pushed)

If two screens share a NavigationStack, capture the root-level view first.

Priming View State

Some screens need to be captured in a specific non-default state — a timer mid-countdown, a chart with particular values, a form half-filled. The pattern:

1. Add a static var to MarketingCapture for each priming value:

   /// Set by the coordinator before presenting the timer view.
   /// The view reads this in .onAppear to jump to a specific elapsed time.
   static var pendingElapsedSeconds: Int?
   
   /// Set to true to show the assessment overlay on the timer.
   static var pendingShowAssessment: Bool = false

2. In the target view, add a DEBUG-gated .onAppear that reads the priming value:

   .onAppear {
       #if DEBUG
       if MarketingCapture.isActive, let elapsed = MarketingCapture.pendingElapsedSeconds {
           phase = .active
           timerVM.elapsedTime = TimeInterval(elapsed)
           timerVM.start()
           DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) { timerVM.pause() }
       }
       #endif
   }

3. In the coordinator, set the var before navigating:

   CaptureStep(
       name: "06-timer-midway",
       navigate: {
           MarketingCapture.pendingElapsedSeconds = 75
           openTimerSheet(someRecipe)
       },
       settle: .milliseconds(2400),
       cleanup: {
           MarketingCapture.pendingElapsedSeconds = nil
           NotificationCenter.default.post(name: MarketingCapture.dismissSheetNotification, object: nil)
       }
   )

Creating a Demo Data Seeder

If the app has no existing demo data mechanism, create one. Place it in <AppName>/Debug/DemoDataSeeder.swift, wrapped in #if DEBUG.

Guidelines:

• Seed enough data that every captured screen looks populated. Audit the screen list against the seed.
• Use realistic content: real place names, plausible numbers, varied states (some items "running low", some "fresh", some with images, some without).
• If the app uses SwiftData, write directly to the ModelContext. If Core Data, use the managed object context. If a REST backend, seed via the local cache/store layer.
• Make seeding idempotent — check if data already exists before inserting. The store persists across simulator relaunches, and re-seeding per locale causes CloudKit sync churn and crashes.
• Include enough variety to fill different UI states: empty states should NOT appear unless they're a marketing screen.

Minimal shape:

#if DEBUG
enum DemoDataSeeder {
    static func seedIfEmpty(in context: ModelContext) {
        let existing = (try? context.fetchCount(FetchDescriptor<Item>())) ?? 0
        guard existing == 0 else { return }

        // Items with varied states
        let items = [
            Item(name: "...", status: .active, ...),
            Item(name: "...", status: .lowStock, ...),
            // ...enough to fill every screen
        ]
        items.forEach { context.insert($0) }
        try? context.save()
    }
}
#endif