Cannot render canvas in XCode

Hi,

Sorry to hear you are having problems getting previews working. This error can often indicate a crash in your application when it launches, or a problem with the simulator. If you look into the folder ~/Library/Logs/DiagnosticReports, do you see any crash reports for your app?

If not, the best next step will be to file a feedback with diagnostics so we can take a look.

Steps to generate helpful diagnostics:

1. Download and install the logging profile on all devices involved. Instructions and profiles are available here: https://developer.apple.com/bug-reporting/profiles-and-logs/?name=swift
2. Reproduce the issue
3. Click the "Diagnostics" button in the error banner in Previews' Canvas area (or if the banner is missing you can use the menu: Editor > Canvas > Diagnostics)
4. In the sheet that appears, click "Generate Report" in the bottom left of the sheet
5. Attach (or make from the folder) the resulting zip file to the bug report (will be named something like previews-diagnostics-0123456789.zip)
6. Generate the sysdiagnose(s) and attach those too