ios-swift-recipes

iOS Swift Recipes — App Store Production Patterns

Use When

• Production Swift recipes from real App Store apps. Covers safe numeric conversion, Codable tricks, custom decoders, type-safe Dictionary extraction, ISO 8601 dates, UIKit navigation/alerts/maps, UIView effects (shadows, gradients, blur), keyboard...
• The task needs reusable judgment, domain constraints, or a proven workflow rather than ad hoc advice.

Do Not Use When

• The task is unrelated to ios-swift-recipes or would be better handled by a more specific companion skill.
• The request only needs a trivial answer and none of this skill's constraints or references materially help.

Required Inputs

• Gather relevant project context, constraints, and the concrete problem to solve; load references only as needed.
• Confirm the desired deliverable: design, code, review, migration plan, audit, or documentation.

Workflow

• Read this SKILL.md first, then load only the referenced deep-dive files that are necessary for the task.
• Apply the ordered guidance, checklists, and decision rules in this skill instead of cherry-picking isolated snippets.
• Produce the deliverable with assumptions, risks, and follow-up work made explicit when they matter.

Quality Standards

• Keep outputs execution-oriented, concise, and aligned with the repository's baseline engineering standards.
• Preserve compatibility with existing project conventions unless the skill explicitly requires a stronger standard.
• Prefer deterministic, reviewable steps over vague advice or tool-specific magic.

Anti-Patterns

• Treating examples as copy-paste truth without checking fit, constraints, or failure modes.
• Loading every reference file by default instead of using progressive disclosure.

Outputs

• A concrete result that fits the task: implementation guidance, review findings, architecture decisions, templates, or generated artifacts.
• Clear assumptions, tradeoffs, or unresolved gaps when the task cannot be completed from available context alone.
• References used, companion skills, or follow-up actions when they materially improve execution.

Evidence Produced

Category	Artifact	Format	Example
Correctness	Recipe usage register	Markdown doc cataloguing applied Swift recipes (numeric conversion, Codable, decoders) per feature	docs/ios/recipe-register.md

References

• Use the references/ directory for deep detail after reading the core workflow below.

Concrete, copy-pasteable Swift from Swift Recipes for iOS Developers (Nekrasov).

---

1. Safe Numeric Conversions

extension Double {
    var asInt16: Int16? { Int16(exactly: self.rounded()) }
    var asInt: Int?     { Int(exactly: self.rounded()) }
}
// Never: Int16(someDouble) — crashes on out-of-range
// Always: someDouble.asInt16 — returns nil safely

// Prices: store as Int cents, never Double
extension Int    { var asPrice: String { String(format: "%d.%02d", self/100, self%100) } }
extension Double {
    var asPrice: String {
        guard let cents = (self * 100.0).asInt else { return "" }
        return String(format: "%d.%02d", cents/100, cents%100)
    }
}

---

Additional Guidance

Extended guidance for ios-swift-recipes was moved to references/skill-deep-dive.md to keep this entrypoint compact and fast to load.

Use that deep dive for:

• 2. Reusable NumberFormatter (Critical for scroll performance)
• 3. ISO 8601 Date Handling
• 4. Encodable/Decodable Universal Extensions
• 5. Custom Decoder — Handle API Type Mismatches
• 6. Type-Safe Dictionary Extraction
• 7. String Validation
• 8. SHA256 Password Hashing with Salt
• 9. UIViewController Navigation Helpers
• 10. UIView Visual Effects (IBDesignable)
• 11. Keyboard Handling — Animated Layout Shift
• 12. UITextField Real-Time Formatting
• 13. UIImage Processing
• Additional deep-dive sections continue in the reference file.