Swift UI Preview is not working on any of the sample projects

📚 Official Books SwiftUI by Tutorials
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I’m getting the following error. I’m running xCode 11.3.1. Have tried restarting xCode, deleting derived data, etc with no success. Does anyone have a workaround for this.

CrashOnLaunchError: RGBullsEye app crashed on launch

The app “RGBullsEye” crashed while updating the preview. Look for crash logs in ~/Library/Logs/DiagnosticReports for more details.

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| Error Domain=FBSOpenApplicationServiceErrorDomain Code=1 “The request to open “com.raywenderlich.RGBullsEye” failed.” UserInfo={BSErrorCodeDescription=RequestDenied, NSLocalizedDescription=The request to open “com.raywenderlich.RGBullsEye” failed., NSUnderlyingError=0x7fbb50ac1f90 {Error Domain=NSPOSIXErrorDomain Code=89 “Operation canceled”}, FBSOpenApplicationRequestID=0x57dc, NSLocalizedFailureReason=The request was denied by service delegate (SketchBoard.SketchBoardSystemService).

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I found this on SO:

This error happens when a previous run of the app is still alive in the background, even if you clicked “Stop” in Xcode. Try manually killing the app in simulator itself: cmd+shift+H twice to open up running apps, drag up your app to kill it. Note cmd+shift+H is the shortcut to go to homescreen. Then start the new run and it should work fine :slight_smile:

Something else I’ve found that can help with mysterious crash-on-open is to delete .xcodeproj/xcuserdata/.xcuserdatad