SwiftUI previews stopped working everywhere after using EnvironmentObject

Question

Created Jul ’19

Replies 14

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Views 18k

Participants 7

I added @EnvironmentObject to a property in a SwiftUI view as part of the official tutorial Adding User Interaction and added the .environmentObject modifier to the preview. However, I get the error:

Cannot preview in this file - MyApp.app may have crashed

This error now appears in every SwiftUI project, even ones without EnvironmentObject or a blank SwiftUI template, so I cannot use previews. I have tried rebooting several times, and made sure the command line tools are set to Xcode 11. How can I fix this? Thanks!

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Answer 1

Claude31 OP

Jul ’19

Did you do an option-clean-build Folder in XCode ?

Did you read the release notes of XCode 11.4:

SwiftUI Tutorials Known Issues

After following Section 7, Step 7 in the Building Lists and Navigation tutorial in Xcode, you might encounter an error in your projectʼs SceneDelegate.swift file. (51334559)

Workaround: Update line 14 of SceneDelegate.swift to use LandmarkList instead of LandmarkDetail:

window.rootViewController = UIHostingController(rootView: LandmarkList())

After following Section 5, Step 3 in the Handling User Input tutorial in Xcode, you might encounter an error in the preview provider. (51341785)

Workaround: Undo the change to the LandmarkDetail initializer, so that you only add the environmentObject(_:) modifier:

struct LandmarkDetail_Preview: PreviewProvider {     
     static var previews: some View {
          LandmarkDetail(landmark: landmarkData[0])
                .environmentObject(UserData())
} }

2

Answer 2

eos-pi OP

Jul ’19

Thanks for the reply! I think that may help that specific app, but SwiftUI previews now crash in every SwiftUI project I have, including projects without EnivronmentObject. I reinstalled Xcode 11, but the problem persists.

The crash report contains this information:

Application Specific Information:
-[MTLSimBuffer initWithDevice:bufferRef:content:pointer:length:options:heap:deallocator:]:89: failed assertion `Invalid storageMode 1'

CoreSimulator 675 - Device: iPhone 8 (E3A5C531-2BD9-4EEE-BC8B-9AFAB54AECF8) - Runtime: iOS 13.0 (17A5534d) - DeviceType: iPhone 8

1

Answer 3

Claude31 OP

Jul ’19

There seem to be a problem with simulator.

Could you either:

- select another device simulator

- remove and reinstall the erroneous one

0

Answer 4

eos-pi OP

Jul ’19

The other preview devices I'm trying seem to have the same issue. I briefly had success running a preview on my physical iPad, but it stopped working. I'll try reinstalling the simulator.

1

Answer 5

eos-pi OP

Jul ’19

Reinstalling the simulator didn't seem to work, and the crash logs still show that it's using a device I deleted. Are the SwiftUI previews different from the simulator?

1

Answer 6

Claude31 OP

Jul ’19

Did you delete and reinstall ?

Could help

https://stackoverflow.com/questions/29076171/how-to-force-reinstall-ios-simulator

1

Answer 7

eos-pi OP

Jul ’19

I deleted from the Devices and Simulators window, which modifies this directory.

~/Library/Developer/CoreSimulator/Devices

Then I reinstalled an iPhone X simulator, but the crash logs still state iPhone 8. I also previously previewed with an iPhone SE, which I didn't have installed as a simulator. It seems like SwiftUI previews are different from the simulator.

1

Answer 8

eos-pi OP

Jul ’19

This output is produced by the error's diagnostics:

Landmarks.app crashed: Error Domain=render service Code=12 "Rendering service was interrupted" UserInfo={NSLocalizedDescription=Rendering service was interrupted}

1

Answer 9

Svantulden OP

Sep ’20

I have this exact issue now!

Once I've added an @EnvironmentObject to my view, built the project, then removed it again, I cannot seem to get any previews working again.

Seems code-independent, as if a SwiftUI cache is still referring to the old Environment object.

@eos-pi: Have you found a solution in the meantime? I've also tried all the known XCode voodoo (didn't help) so it might only be solved by a clean install of MacOS? 😨

1

Answer 10

MCosta OP

Feb ’21

I had an similar issue to this one.

Turns out it was linked to me mapping a shortcut for Canvas > Automatically Refresh Canvas and hitting it pretty much every 10 seconds.
As soon as I remapped my shortcut to Canvas > Refresh Canvas instead the issue disappeared instantly.

2

Answer 11

jsonliu OP

Jul ’21

https://developer.apple.com/forums/thread/120541?answerId=681414022#681414022

0

Answer 12

jsonliu OP

Jul ’21

Working on the tutorial on XCode 12.5.1 Getting error until the Step 7. This is how is solve the issue on LandmarkList

struct LandmarkList_Previews: PreviewProvider {
  static var modelData = ModelData()
  static var previews: some View {
    ForEach(["iPhone 12 Pro Max"], id: \.self) { deviceName in
      LandmarkList().environmentObject(modelData)
        .previewDevice(PreviewDevice(rawValue: deviceName))
        .previewDisplayName(deviceName)
    }
  }
}

1

Answer 13

goldena OP

Dec ’21

Step 1: Delete everything from: ~/Library/Developer/Xcode/UserData/Previews/Simulator Devices/

Step 2: Run in the terminal: killall -9 com.apple.CoreSimulator.CoreSimulatorService

Kudos to the authors: https://stackoverflow.com/a/63384526/13407134

2

Answer 14

mhteas OP

Jan ’22

I'm seeing the same problem with Xcode 13.2.1, but the above steps isn't fixing it. Anyone seen a further workaround yet? I'm trying:

Quit Xcode
quit simulator
delete files as above
killall as above.

But I'm still getting preview not working.

0