Ios App Development Shipping

---
name: ios-app-development-shipping
description: "Build, test, and ship iOS apps with Swift, Xcode, and App Store best practices."
category: "Development"
author: community
version: "1.0.0"
icon: code
---

# iOS Development Rules

## Xcode & Build
- Clean build folder (Cmd+Shift+K) fixes most "impossible" build errors — derived data gets corrupted regularly
- Simulator reset (Device > Erase All Content and Settings) clears cached app state that survives reinstalls
- Archive builds use Release config — bugs that only appear in production often stem from optimization differences
- `xcodebuild -showsdks` lists available SDKs — useful when builds fail with "SDK not found"
- Parallel builds can cause race conditions in script phases — add input/output file lists to enforce ordering

## Code Signing
- "No signing certificate" usually means certificate is expired or revoked — check in Keychain Access, not just Xcode
- Provisioning profiles embed device UDIDs — new test device requires profile regeneration and reinstall
- Automatic signing fails in CI — always use manual signing with exported credentials for builds
- Distribution certificates are limited to 3 per account — don't create new ones, export and share the existing one
- After renewing a certificate, update ALL provisioning profiles that used the old one

## SwiftUI Patterns
- `@State` for view-local data, `@StateObject` for owned ObservableObjects, `@ObservedObject` for passed-in objects — mixing them wrong causes crashes or lost state
- `List` with `id: \.self` on non-Hashable types causes silent failures — always use explicit `id` parameter with stable identifiers
- `task` modifier cancels automatically on view disappear — no manual cancellation needed, but check `Task.isCancelled` in loops
- Previews crash silently with real network calls — use mock data or dependency injection for previews
- `@Environment` values are nil in previews unless explicitly provided — wrap previews in container with environment set

## App Store Rules
- Apps must work offline or show clear offline state — silent failures cause rejection
- Login must be skippable if app has non-account features — reviewers reject mandatory login for content browsing
- "Sign in with Apple" is required if you offer any third-party social login — no exceptions
- Privacy labels must match actual data collection — Apple verifies and rejects mismatches
- In-app purchases must use StoreKit for digital goods — external payment links get rejected

## Info.plist Requirements
- `ITSAppUsesNonExemptEncryption = NO` avoids export compliance questions for most apps — add it to skip the daily annoyance
- Camera/microphone/location usage descriptions are mandatory — missing them crashes the app on access attempt
- `LSApplicationQueriesSchemes` must list URL schemes before `canOpenURL` works — iOS 9+ security requirement
- `UIRequiresFullScreen = YES` on iPad opts out of multitasking — use only if your app truly can't support split view

## Performance
- `Instruments > Time Profiler` reveals actual bottlenecks — don't guess, measure
- Images in Assets.xcassets get optimized automatically — loose files in bundle don't
- `@MainActor` annotation ensures UI updates happen on main thread — missing it causes random crashes under load
- Memory leaks often hide in closures — use `[weak self]` in escaping closures that reference `self`
- `List` with thousands of items is fast, `ForEach` in `ScrollView` is not — List uses cell reuse, ScrollView loads everything

## Debugging
- `po` in LLDB prints object description, `p` prints raw value — use `po` for most debugging
- Purple warnings in Console indicate main thread violations — fix these, they cause jank
- `-com.apple.CoreData.SQLDebug 1` in launch arguments shows all Core Data queries — essential for debugging fetch performance
- Crash logs without symbols are useless — keep dSYM files for every release build
- TestFlight crashes appear in Xcode Organizer — check there, not just in App Store Connect