Name: iOS
Availability: InStock
Author: ivangdavila

iOS Development Rules

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

"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

```
@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

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

```
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

```
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

```
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

iOS