Xcode SwiftUI Preview Not Working or Crashing

How to fix it

Try these in order — the most common fix is first.

1. 1. Make the project build

   1. Press Cmd-B and fix errors first; previews need a successful build
   Did this fix it? Yes No

2. 2. Resume and rebuild the preview

   Copy steps
   1. Press Option-Cmd-P to refresh
   2. Choose a different preview device in the canvas
   Did this fix it? Yes No

3. 3. Clear preview data

   Copy steps
   1. Quit Xcode
   2. Delete ~/Library/Developer/Xcode/UserData/Previews
   3. Delete the project's DerivedData and reopen
   Did this fix it? Yes No

4. 4. Fix preview code

   Copy steps
   1. Provide mock data and environment objects in the #Preview block
   2. Wrap code that needs a device in conditional checks
   Did this fix it? Yes No

5. 5. Check the diagnostics

   1. Click the diagnostics button in the canvas and read the crash report
   Did this fix it? Yes No

Symptoms

The canvas shows 'Failed to build', 'Cannot preview in this file', or 'Preview crashed' and the Resume button does nothing.

Why it happens

• The target does not build
• Preview code uses unavailable types or missing environment objects
• Corrupted preview cache
• Wrong run destination selected

This guide also covers

• swiftui preview not working
• xcode preview crashed
• xcode canvas failed to build

Other Xcode errors

• Xcode Simulator Not Launching or Won't Boot
• Xcode 'Unable to Install' App Error
• Xcode 'No Profiles Found' Code Signing Error
• Xcode 'Failed to Register Bundle Identifier' Error
• Xcode Indexing Stuck or Taking Forever
• Xcode Doesn't Show My iPhone (Device Not Detected)
• Xcode Taking Too Much Storage (How to Free 50GB+)
• Xcode 'Build Failed' With No Clear Error