Error fetching view hierarchy

Question

Created Aug ’16

Replies 3

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Ever since the beta of XC8 was released, the View Hierarchy browser (an amazing tool when it works) seems to have broken. I was able to get it working once, and only once on a specific device. The next time I try I get something like:

Error: Unable to capture view hierarchy.

Details: Error fetching view hierarchy: (

"Exception gathering view hierarchy information: snapshot method cannot be called from within draw"

)

Method: -[DBGAbstractViewDescriber handleFetchedViewInfo:fetchError:resultHandler:]

Please file a bug at http://bugreport.apple.com with this warning message and any useful information you can provide.

Where the UI view would normally be is "Unable to capture view hierarchy. Check the console log for more information"

Anyone else see this?

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Answer 1

Challenger OP

Sep ’16

Same problem here, looking forward for workaround. However, you can still print view hierarchy using lldb.

// First you need to get viewControllers hierarchy
po [[[UIWindow keyWindow] rootViewController] _printHierarchy]
// Next step is to get a UIView's adress of appeared controller
po [<UIView adress> recursiveDescription]

0

Answer 2

jason_123 OP

Oct ’16

New to iOS dev but not new to coding. Using XCode 8.0 and going through the FoodTracker tutorial I am receiving what seems to be a similar error message in Lesson 4 (Work with View Controllers). The provided code also gives the same error message. It happens when I click on the ImageView in the simulator. It says "Thread 9: signal SIGABRT" which I take to mean an exception was thrown and not handled by the app. I added a breakpoint for all exceptions but the breakpoint isn't catching anything and I'm not sure what the error is telling me to fix.

Error:

Unable to capture view hierarchy.

Details: Error fetching view hierarchy: (

"Exception gathering view hierarchy information: -[UIApplication _performWithUICACommitStateSnapshotting:] must be called on the main thread

(

0 CoreFoundation

0x000000010420434b __exceptionPreprocess + 171

1 libobjc.A.dylib

0x000000010156521e objc_exception_throw + 48

2 CoreFoundation

0x0000000104208442 +[NSException raise:format:arguments:] + 98

3 Foundation

0x0000000101131e09 -[NSAssertionHandler handleFailureInFunction:file:lineNumber:description:] + 166

4 UIKit

0x0000000101a407c2 -[UIApplication _performWithUICACommitStateSnapshotting:] + 305

5 UIKit

0x0000000101dd2ecc +[UIScreen _beginDisableScreenUpdatesForSnapshotUsingSnapshotCover:] + 622

6 UIKit

0x0000000101ad59a3 __53-[UIView drawViewHierarchyInRect:afterScreenUpdates:]_block_invoke + 40

7 UIKit

0x0000000101afefcc +[_UIReplicantView _pendingSnapshotOfTarget:snapshotBlock:] + 705

8 UIKit

0x0000000101ad588c -[UIView drawViewHierarchyInRect:afterScreenUpdates:] + 263

9 libViewDebuggerSupport.dylib

0x000000010101ad9f +[DBGViewDebuggerSupport_iOS _renderEffectViewUsingDrawHierarchyInRect:] + 2081

10 libViewDebuggerSupport.dylib

0x000000010101a07d +[DBGViewDebuggerSupport_iOS snapshotView:errorString:] + 524

11 libViewDebuggerSupport.dylib

0x000000010101d8ac +[DBGViewDebuggerSupport _snapshotView:andAddDataToDictionary:] + 82

12 libViewDebuggerSupport.dylib

0x000000010101d5d6 +[DBGViewDebuggerSupport collectViewInfo:] + 178

13 libViewDebuggerSupport.dylib

0x000000010101def4 +[DBGViewDebuggerSupport _collectSubviewInfoForView:encodeLayers:] + 43

14 libViewDebuggerSupport.dylib