SwiftUI @State Updates Not Reflecting in UI Until View Reconstruction (Xcode Preview & Device)

Question

Created 13h

Replies 1

Boosts 0

Participants 2

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!

Boost

Answer 1

darkpaw OP

5h

Can't do much with the code as provided.

Please reply with the code within the code block. Use the formatting tools to do this, or just type three backticks (`) in a row at the start and end of your code.

And please ensure all relevant code is present.

Example:

import SwiftUI

struct ContentView: View {
  var body: some View {
    ...
  }
}

0