Xcode SwiftUI preview failed to build
Use the preview diagnostic and a normal target build to separate compiler errors from preview runtime problems.
Use the preview diagnostic and a normal target build to separate compiler errors from preview runtime problems.
Try these fixes in order
Build the target first
Run a normal build for the same destination and fix the earliest compiler error.
Inspect preview diagnostics
Open the canvas diagnostic report and note which file, target, or dependency failed.
Simplify preview inputs
Use a small Preview with deterministic sample data; avoid network or unavailable environment objects during initialization.
Check runtime and scheme
Confirm the preview destination and active scheme support the view and dependencies.
Interpret what you see
The normal build also fails
What it suggests: Preview is surfacing a real compiler or dependency error.
Next check: Fix the first build diagnostic for the same target and destination.
Only the preview fails during initialization
What it suggests: The view may require live network state or an environment object unavailable in preview.
Next check: Inject deterministic sample state and a minimal Preview to locate the dependency.
One preview works but another does not
What it suggests: The failure is likely in that view’s data or configuration.
Next check: Reduce the failing preview to a simple view and add modifiers and dependencies back incrementally.
Why this happens
- The target has a compilation or dependency error.
- Preview initialization depends on unavailable data or services.
Still not working?
If a normal build passes but preview alone fails, reduce the preview to a minimal view and add sample dependencies back one at a time.
Official sources
These steps are based on the linked documentation and general diagnostics. BugMedic has not independently tested every product and system configuration. Review commands before running them.