Hi, I have an issue with app preview

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Created 3d

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I can't seem to access preview for any of my views in any of my swift projects at all (using Mac to code and using iPhone 16 pro as preview and simulation, simulation can work), even after restarting Mac and Xcode itself. The preview section has a popup saying "Cannot preview in this file, unexpected error occured" (for every file), please tell me what is wrong and help me solve it to see the preview, thank you!

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Developer Tools Engineer OP

Apple

3d

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 or for anything where the timestamps line up with your attempt to use previews?

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

We will need the diagnostics Xcode Previews generates in order to make sure we understand the error the previews system is encountering.

Install the logging profile using instructions available here: https://developer.apple.com/bug-reporting/profiles-and-logs/?name=swift On your mac running Xcode, and on your physical preview device (if you are using one).

Install the logging profile using the following instructions on your mac running Xcode; and if you are using one, your physical preview device (iOS or visionOS): https://developer.apple.com/bug-reporting/profiles-and-logs/?name=swift

Then when you reproduce the problem in Xcode:

Either (a) an error banner will appear, click the "Diagnostics" button in that banner; or (b) if you're not seeing an error but you still want to provide diagnostics you can get the same diagnostics window by going under the Editor menu in the menu bar, then selecting the Canvas submenu, then selecting "Diagnostics".
In the sheet that appears, click "Generate Report" in the bottom left of the sheet
Attach (or make from the folder) the resulting zip file to the bug (will be named something like previews-diagnostics-0123456789.zip)
Generate a sysdiagnose on your mac and any on-device preview devices

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