Xcode 11: SwiftUI preview not working

I created a simple test project in Xcode 11 (on Catalina) and was able to see the previews for the SwiftUI views and their settings etc.


I then opened an small established project I have and did all the updates that Xcode 11 suggested to bring it up to spec. Then I added a SwiftUI view using the SwiftUI template. Everything compiles fine, but when I attempt to see the preview of the SwiftUI view I get this error:


messageRepliedWithError("Connecting to launched interactive agent 1590", 
Optional(Error Domain=com.apple.dt.ultraviolet.service Code=17 
"connectToPreviewHost: Failed to connect to 1590: Error Domain=com.apple.dt.ProcessAttachUtilities Code=3 
"Target process 1590 exited prematurely, likely crashed" 
UserInfo={NSLocalizedDescription=Target process 1590 exited prematurely, likely crashed}" 
UserInfo={NSLocalizedDescription=connectToPreviewHost: Failed to connect to 1590: 
Error Domain=com.apple.dt.ProcessAttachUtilities Code=3 "Target process 1590 exited prematurely, likely crashed" 
UserInfo={NSLocalizedDescription=Target process 1590 exited prematurely, likely crashed}}))


I've tried all sorts of things and looked for settings I might have missed but so far I've not been able to figure this out (also rebooted the machine).


Anyone happen to come across this and figure it out?

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drekka
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Digging around in the crash logs I found references to the Thread Sanitizer. So I turned it off and now I have this error:


Points Master.app: Error Domain=com.apple.dt.UITestingAgent Code=-1 
"Preview provider "13Points_Master17MainView_PreviewsV" does not exist" 
UserInfo={NSLocalizedDescription=Preview provider "13Points_Master17MainView_PreviewsV" does not exist}


So I was thinking one step a head then I figured out my project didn't have the 'DEBUG' active compilation condition so the SwiftUI preview functions where not visible to Xcode.


It's all now working.

Posted by
drekka
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Digging around in the crash logs I found references to the Thread Sanitizer. So I turned it off and now I have this error:


Points Master.app: Error Domain=com.apple.dt.UITestingAgent Code=-1 
"Preview provider "13Points_Master17MainView_PreviewsV" does not exist" 
UserInfo={NSLocalizedDescription=Preview provider "13Points_Master17MainView_PreviewsV" does not exist}


So I was thinking one step a head then I figured out my project didn't have the 'DEBUG' active compilation condition so the SwiftUI preview functions where not visible to Xcode.


It's all now working.

Posted by
drekka
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