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SwiftUI @State Updates Not Reflecting in UI Until View Reconstruction (Xcode Preview & Device)
Issue Description I'm experiencing a bizarre SwiftUI state update issue that only occurs in Xcode development environment (both Canvas preview and device debugging), but does not occur in production builds downloaded from App Store. Symptom: User taps a button that modifies a @State variable inside a .sheet Console logs confirm the state HAS changed But the UI does not update to reflect the new state Switching to another file in Xcode and back to ContentView instantly fixes the issue The production build (same code) works perfectly fine Environment Xcode: 16F6 (17C52) iOS: 26.2 (testing on iPhone 13) macOS: 25.1.0 (Sequoia) SwiftUI Target: iOS 15.6+ Issue: Present in both Xcode Canvas and on-device debugging Production: Same code works correctly in App Store build (version 1.3.2) Code Structure Parent View (ContentView.swift) struct ContentView: View { @State private var selectedSound: SoundTheme = .none @State private var showSoundSheet = false var body: some View { VStack { // Display button shows current selection SettingButton( title: "Background Sound", value: getLocalizedSoundName(selectedSound) // ← Not updating ) { showSoundSheet = true } } .sheet(isPresented: $showSoundSheet) { soundSelectionView } } private var soundSelectionView: some View { ForEach(SoundTheme.allCases) { sound in Button { selectedSound = sound // ← State DOES change (confirmed in console) // Audio starts playing correctly audioManager.startAmbientSound(sound) } label: { Text(sound.name) } } } private func getLocalizedSoundName(_ sound: SoundTheme) -> String { // Returns localized name return sound.localizedName }} What I've Tried Attempt 1: Adding .id() modifier SettingButton(...) .id(selectedSound) // Force re-render when state changes Result: No effect Attempt 2: Moving state modification outside withAnimation // Before (had animation wrapper):withAnimation { selectedSound = sound}// After (removed animation):selectedSound = sound Result: No effect Attempt 3: Adding debug print() statements selectedSound = soundprint("State changed: (selectedSound)") // ← Adding this line FIXES the issue! Result: Mysteriously fixes the issue! But removing print() breaks it again. This suggests a timing/synchronization issue in Xcode's preview system. Observations What works: ✅ Console logs confirm state changes correctly ✅ Switching files in Xcode triggers view reconstruction → everything works ✅ Production build from App Store works perfectly ✅ Adding print() statements "fixes" it (likely changes execution timing) What doesn't work: ❌ Initial file load in Xcode ❌ Hot reload / incremental updates ❌ Both Canvas preview and on-device debugging Workaround that works: Click another file in Xcode Click back to ContentView.swift Everything works normally Key Question Is this a known issue with Xcode 16's SwiftUI preview/hot reload system? The fact that: Same exact code works in production Adding print() "fixes" it File switching triggers reconstruction that fixes it ...all suggest this is an Xcode tooling issue, not a code bug. However, it makes development extremely difficult as I can't reliably test changes without constantly switching files or killing the app. What I'm Looking For Confirmation: Is this a known Xcode 16 issue? Workaround: Any better solution than constantly switching files? Root cause: What's causing this state update timing issue? Any insights would be greatly appreciated!
Topic: UI Frameworks SubTopic: SwiftUI
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Dec ’25