data-export

Data Export Generator

Generate production data export and import infrastructure -- JSON export via Codable, CSV generation with proper escaping, PDF report rendering with UIGraphicsPDFRenderer, GDPR-compliant full data export, file import with UTType-based picker, and share sheet integration. No third-party dependencies.

When This Skill Activates

Use this skill when the user:

• Asks to "add data export" or "export user data"
• Wants "CSV export" or "JSON export" or "PDF export"
• Mentions "GDPR data portability" or "right to data portability"
• Asks about "exporting all user data" for compliance
• Wants to "import data" from files or competitor apps
• Mentions "share sheet" for exporting data
• Asks about "data backup" or "data download"

Pre-Generation Checks

1. Project Context Detection

• [ ] Check deployment target (iOS 16+ / macOS 13+)
• [ ] Check Swift version (requires Swift 5.9+)
• [ ] Identify data model layer (SwiftData, Core Data, custom structs)
• [ ] Identify source file locations

2. Existing Export Detection

Search for existing export code:

Glob: **/*Export*.swift, **/*Import*.swift, **/*CSV*.swift, **/*PDF*.swift
Grep: "UIGraphicsPDFRenderer" or "CSVExport" or "UIActivityViewController" or "ShareLink" or "fileExporter"

If existing export code found:

• Ask if user wants to replace or add additional formats
• Identify which formats are already supported

3. Data Model Detection

Search for data models that need exporting:

Grep: "@Model" or "NSManagedObject" or "struct.*Codable" or "class.*Codable"

Identify the models to build export conformances for.

Configuration Questions

Ask user via AskUserQuestion:

1. Export formats needed?

• JSON (structured, machine-readable, best for GDPR)
• CSV (tabular data, spreadsheet-compatible)
• PDF (formatted reports with headers, tables, branding)
• Multiple (select which combination)

1. What data needs exporting?

• All user data -- GDPR compliance (every piece of stored user data)
• Specific data types (user selects which models to export)
• Reports/summaries (aggregated data, not raw records)

1. Do you need import capability?

• No -- export only
• Yes -- from files (JSON, CSV via file picker)
• Yes -- from competitor apps (custom format parsing)

1. How should users trigger export?

• Share sheet (system share UI with multiple destinations)
• Settings screen (dedicated export section)
• Export button (inline in content views)
• Automatic backup (periodic export to iCloud/local)

Generation Process

Step 1: Read Templates

Read templates.md for production Swift code.

Step 2: Create Core Files

Generate these files:

1. DataExportManager.swift -- Central export coordinator with format routing
2. DataExportable.swift -- Protocol for models that support export

Step 3: Create Format-Specific Files

Based on configuration:

1. CSVExporter.swift -- If CSV format selected
2. PDFExporter.swift -- If PDF format selected

Step 4: Create Import Files

If import capability selected:

1. DataImporter.swift -- File picker and format parser

Step 5: Determine File Location

Check project structure:

• If Sources/ exists -> Sources/DataExport/
• If App/ exists -> App/DataExport/
• Otherwise -> DataExport/

Output Format

After generation, provide:

Files Created

DataExport/
├── DataExportable.swift   # Protocol for exportable models
├── DataExportManager.swift # Central export coordinator
├── CSVExporter.swift       # CSV generation (optional)
├── PDFExporter.swift       # PDF rendering (optional)
└── DataImporter.swift      # File import (optional)

Integration with Data Models

Make a model exportable:

struct Expense: Codable, DataExportable {
    let id: UUID
    let title: String
    let amount: Double
    let date: Date
    let category: String

    // DataExportable conformance
    static var csvHeaders: [String] {
        ["ID", "Title", "Amount", "Date", "Category"]
    }

    var csvRow: [String] {
        [id.uuidString, title, String(format: "%.2f", amount),
         ISO8601DateFormatter().string(from: date), category]
    }

    var pdfDescription: String {
        "\(title) - $\(String(format: "%.2f", amount)) (\(category))"
    }
}

Export from a view:

struct ExpenseListView: View {
    let expenses: [Expense]
    @State private var exportURL: URL?
    @State private var showShareSheet = false

    var body: some View {
        List(expenses) { expense in
            ExpenseRow(expense: expense)
        }
        .toolbar {
            Menu {
                Button("Export as JSON") {
                    Task { await exportAs(.json) }
                }
                Button("Export as CSV") {
                    Task { await exportAs(.csv) }
                }
                Button("Export as PDF") {
                    Task { await exportAs(.pdf) }
                }
            } label: {
                Label("Export", systemImage: "square.and.arrow.up")
            }
        }
        .sheet(isPresented: $showShareSheet) {
            if let exportURL {
                ShareSheet(activityItems: [exportURL])
            }
        }
    }

    private func exportAs(_ format: DataExportManager.ExportFormat) async {
        do {
            exportURL = try await DataExportManager.shared.export(
                expenses, format: format, filename: "expenses"
            )
            showShareSheet = true
        } catch {
            // Handle error
        }
    }
}

SwiftUI ShareLink (iOS 16+):

if let url = exportURL {
    ShareLink(item: url) {
        Label("Share Export", systemImage: "square.and.arrow.up")
    }
}

Import from file picker:

struct ImportView: View {
    @State private var showFilePicker = false
    @State private var importedItems: [Expense] = []

    var body: some View {
        Button("Import Data") { showFilePicker = true }
            .fileImporter(
                isPresented: $showFilePicker,
                allowedContentTypes: DataImporter.supportedTypes
            ) { result in
                Task {
                    let url = try result.get()
                    importedItems = try await DataImporter.importFile(
                        from: url, as: Expense.self
                    )
                }
            }
    }
}

GDPR Data Portability

For full GDPR compliance, export ALL user data:

func exportAllUserData() async throws -> URL {
    let allData = GDPRExportData(
        profile: try await fetchUserProfile(),
        expenses: try await fetchAllExpenses(),
        settings: try await fetchUserSettings(),
        exportDate: Date(),
        appVersion: Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? "1.0"
    )

    let encoder = JSONEncoder()
    encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
    encoder.dateEncodingStrategy = .iso8601
    let data = try encoder.encode(allData)

    let url = FileManager.default.temporaryDirectory
        .appendingPathComponent("user-data-export.json")
    try data.write(to: url)
    return url
}

Testing

@Test
func jsonExportRoundTrip() async throws {
    let expenses = [
        Expense(id: UUID(), title: "Coffee", amount: 4.50,
                date: Date(), category: "Food")
    ]

    let url = try await DataExportManager.shared.export(
        expenses, format: .json, filename: "test"
    )
    let data = try Data(contentsOf: url)
    let decoded = try JSONDecoder().decode([Expense].self, from: data)

    #expect(decoded.count == 1)
    #expect(decoded.first?.title == "Coffee")
}

@Test
func csvExportFormatsCorrectly() {
    let expenses = [
        Expense(id: UUID(), title: "Coffee, Large", amount: 4.50,
                date: Date(), category: "Food")
    ]

    let csv = CSVExporter.generate(
        from: expenses,
        headers: Expense.csvHeaders,
        rowMapper: { $0.csvRow }
    )

    #expect(csv.contains("\"Coffee, Large\""))  // Commas escaped with quotes
    #expect(csv.hasPrefix("ID,Title,Amount,Date,Category"))
}

@Test
func importParsesCSV() async throws {
    let csvContent = "ID,Title,Amount\n1,Coffee,4.50\n2,Lunch,12.00"
    let url = FileManager.default.temporaryDirectory.appendingPathComponent("test.csv")
    try csvContent.write(to: url, atomically: true, encoding: .utf8)

    let rows = try CSVExporter.parse(from: url)
    #expect(rows.count == 2)
    #expect(rows.first?["Title"] == "Coffee")
}

Common Patterns

Export to Temporary File for Sharing

Always export to a temporary directory, then present via share sheet:

let url = FileManager.default.temporaryDirectory
    .appendingPathComponent("export.\(format.fileExtension)")
try data.write(to: url)
// Present via UIActivityViewController or ShareLink

GDPR Export Should Include Everything

For GDPR Article 20 compliance, export must include:

• All personal data the user provided
• All data generated about the user
• With clear field descriptions

CSV Must Handle Special Characters

Wrap fields containing commas, quotes, or newlines in double quotes; escape internal quotes by doubling them.

Gotchas

Temporary Files Cleanup

Delete large export files after sharing completes rather than relying on the system's periodic cleanup.

PDF Rendering on Background Thread

UIGraphicsPDFRenderer must be used on the main thread if it references UIKit views. For data-only PDF generation (text, lines, rectangles), it is safe to render on a background thread.

Large Dataset Memory

For exporting thousands of records, stream the output instead of building the entire string/data in memory. Write CSV line-by-line to a file handle. For JSON, use JSONSerialization with streams.

ShareLink vs UIActivityViewController

Use ShareLink for the simple case; use UIActivityViewController when you need excluded activities, completion handlers, or custom activities.

File Import Security Scoped URLs

.fileImporter URLs are security-scoped: call url.startAccessingSecurityScopedResource() before reading, url.stopAccessingSecurityScopedResource() after.

References

• templates.md -- All production Swift templates for data export/import
• UIGraphicsPDFRenderer
• UIActivityViewController
• UniformTypeIdentifiers
• GDPR Article 20 - Right to Data Portability
• Related: generators/settings-screen -- Settings screen with export button
• Related: generators/account-deletion -- Account deletion includes data export option