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I have a situation where try NSAttributedString(data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil) crashes the app.

In the console it says: Assertion failure in void _prepareForCAFlush(UIApplication *__strong)()

The function is called in an extension String. When I 'po' values in the console:

(lldb) po self <p>Obfuscated string\n</p> (lldb) po data` 450 bytes count : 450 pointer : 0x00007fd283d75630 pointerValue : 140542131787312 (lldb) po NSAttributedString(data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil) Obfuscated string { NSColor = "kCGColorSpaceModelRGB 0 0 0 1 "; NSFont = "<UICTFont: 0x7fd283c47330> font-family: \"Helvetica\"; font-weight: normal; font-style: normal; font-size: 15.00pt"; NSKern = 0; NSParagraphStyle = "Alignment 4, LineSpacing 0, ParagraphSpacing 15, ParagraphSpacingBefore 0, HeadIndent 0, TailIndent 0, FirstLineHeadIndent 0, LineHeight 19/0, LineHeightMultiple 0, LineBreakMode 0, Tabs (\n), DefaultTabInterval 36, Blocks (\n), Lists (\n), BaseWritingDirection 0, HyphenationFactor 0, TighteningForTruncation NO, HeaderLevel 0"; NSStrokeColor = "kCGColorSpaceModelRGB 0 0 0 1 "; NSStrokeWidth = 0; }

The string exists in a label, that is displayed in a UITableViewCell. The function crashes in a specific case, when the "keyboard frame changes". The Table Cells are being drawn again by iOS and this causes to redraw their content.

The crash happens on the main thread, so the function is being called on the main thread.

What could be the cause of this crash and how could I possibly resolve it?

EDIT: Table view cell code

UITableViewDataSource to generate the cell:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cellID = cellIdentifier(for: message) let cell = tableView.dequeueReusableCell(withIdentifier: cellID) as! MessageTableViewCell cell.message = message cell.setOutletValues() cell.selectionStyle = .none cell.delegate = self return cell }

Implementaion of the Cell:

class MessageTableViewCell: UITableViewCell { var message: Message! // Message Body View @IBOutlet weak var messageBodyView: ZeroPaddingTextView! func setOutletValues() { setMessageBodyOutletValues() } internal func setMessageBodyOutletValues() { if let body = message.body { messageBodyView.attributedText = body.htmlToPlainAttributedString() } } }

And the function to create a plain attributed string, it does a few additions tothe HTML for styling (this is due to the content that comes in through the API, it needs some additions).

func htmlToPlainAttributedString() -> NSAttributedString { let contentString = replacingOccurrences(of: "\n", with: "<br>") let styleSheet = "body {font-family: sans-serif; font-size: 15px; color: #000000;}\n a {text-decoration: none;}\n" let body = "<body>\(contentString)</body>" let html = "<html><head><style type=\"text/css\">\(styleSheet)</style></head>\(body)</html>" if let data = html.data(using: String.Encoding.unicode, allowLossyConversion: true) { do { return try NSAttributedString(data: data, options: [ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil) } catch { return NSAttributedString() } } return NSAttributedString() }

Console crash output:

2017-09-05 22:37:14.692 trustedfamily-ios[70389:10080542] *** Assertion failure in void _prepareForCAFlush(UIApplication *__strong)(), /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3600.7.47/UIApplication.m:2395 2017-09-05 22:38:14.532 trustedfamily-ios[70389:10080542] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'unexpected start state' *** First throw call stack: ( 0 CoreFoundation 0x000000010452ab0b __exceptionPreprocess + 171 1 libobjc.A.dylib 0x00000001035e8141 objc_exception_throw + 48 2 CoreFoundation 0x000000010452ecf2 +[NSException raise:format:arguments:] + 98 3 Foundation 0x00000001031b769b -[NSAssertionHandler handleFailureInFunction:file:lineNumber:description:] + 165 4 UIKit 0x0000000105a31575 _prepareForCAFlush + 499 5 UIKit 0x0000000105a6346b _beforeCACommitHandler + 15 6 CoreFoundation 0x00000001044d0717 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23 7 CoreFoundation 0x00000001044d0687 __CFRunLoopDoObservers + 391 8 CoreFoundation 0x00000001044b5038 CFRunLoopRunSpecific + 440 9 UIFoundation 0x000000010a103edc -[NSHTMLReader _loadUsingWebKit] + 1954 10 UIFoundation 0x000000010a10522a -[NSHTMLReader attributedString] + 22 11 UIFoundation 0x000000010a09ded6 _NSReadAttributedStringFromURLOrData + 8926 12 UIFoundation 0x000000010a09bb64 -[NSAttributedString(NSAttributedStringUIFoundationAdditions) initWithData:options:documentAttributes:error:] + 117 13 trustedfamily-ios 0x0000000101e9e6ad _TTOFE5UIKitCSo18NSAttributedStringcfzT4dataV10Foundation4Data7optionsGVs10DictionarySSP__18documentAttributesGSqGVs33AutoreleasingUnsafeMutablePointerGSqCSo12NSDictionary____S0_ + 173 14 trustedfamily-ios 0x0000000101e9d9d9 _TFE5UIKitCSo18NSAttributedStringCfzT4dataV10Foundation4Data7optionsGVs10DictionarySSP__18documentAttributesGSqGVs33AutoreleasingUnsafeMutablePointerGSqCSo12NSDictionary____S0_ + 89 15 trustedfamily-ios 0x0000000101e9d803 _TFE17trustedfamily_iosSS27htmlToPlainAttributedStringfT_CSo18NSAttributedString + 1459 16 trustedfamily-ios 0x00000001020152f9 _TFC17trustedfamily_ios20MessageTableViewCell26setMessageBodyOutletValuesfT_T_ + 601 17 trustedfamily-ios 0x0000000102013467 _TFC17trustedfamily_ios20MessageTableViewCell15setOutletValuesfT_T_ + 103 18 trustedfamily-ios 0x0000000101f9a22f _TFC17trustedfamily_ios32ConversationDetailViewController9tableViewfTCSo11UITableView12cellForRowAtV10Foundation9IndexPath_CSo15UITableViewCell + 1199 19 trustedfamily-ios 0x0000000101f9a4d7 _TToFC17trustedfamily_ios32ConversationDetailViewController9tableViewfTCSo11UITableView12cellForRowAtV10Foundation9IndexPath_CSo15UITableViewCell + 87 20 UIKit 0x0000000105ba4ab2 -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 750 21 UIKit 0x0000000105ba4cf8 -[UITableView _createPreparedCellForGlobalRow:willDisplay:] + 74 22 UIKit 0x0000000105b79639 -[UITableView _updateVisibleCellsNow:isRecursive:] + 2845 23 UIKit 0x0000000105b774a4 -[UITableView _setNeedsVisibleCellsUpdate:withFrames:] + 201 24 UIKit 0x0000000105b9626a -[UITableView _rectChangedWithNewSize:oldSize:] + 1267 25 UIKit 0x0000000105b96a5c -[UITableView setBounds:] + 322 26 UIKit 0x0000000105adee73 -[UIView(Geometry) _applyISEngineLayoutValuesToBoundsOnly:] + 598 27 UIKit 0x0000000105adf15e -[UIView(Geometry) _resizeWithOldSuperviewSize:] + 125 28 UIKit 0x000000010648f0e9 -[UIScrollView(_UIOldConstraintBasedLayoutSupport) _resizeWithOldSuperviewSize:] + 46 29 CoreFoundation 0x00000001044bb652 __53-[__NSArrayM enumerateObjectsWithOptions:usingBlock:]_block_invoke + 114 30 CoreFoundation 0x00000001044bb56f -[__NSArrayM enumerateObjectsWithOptions:usingBlock:] + 335 31 UIKit 0x0000000105addbcc -[UIView(Geometry) resizeSubviewsWithOldSize:] + 183 32 UIKit 0x00000001063fa16d -[UIView(AdditionalLayoutSupport) _is_layout] + 168 33 UIKit 0x0000000105aea0a6 -[UIView(Hierarchy) _updateConstraintsAsNecessaryAndApplyLayoutFromEngine] + 994 34 UIKit 0x0000000105afb55b -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1268 35 QuartzCore 0x00000001057a4904 -[CALayer layoutSublayers] + 146 36 QuartzCore 0x0000000105798526 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 370 37 UIKit 0x0000000105ae9334 -[UIView(Hierarchy) layoutBelowIfNeeded] + 1108 38 trustedfamily-ios 0x0000000101fe3f4c _TFC17trustedfamily_ios32ConversationDetailViewController28changeBottomLayoutConstraintfT2toV12CoreGraphics7CGFloat_T_ + 284 39 trustedfamily-ios 0x0000000101fe3fac _TToFC17trustedfamily_ios32ConversationDetailViewController28changeBottomLayoutConstraintfT2toV12CoreGraphics7CGFloat_T_ + 44 40 trustedfamily-ios 0x0000000101fe3bf7 _TFFC17trustedfamily_ios32ConversationDetailViewController28changeBottomLayoutConstraintFT2toV12CoreGraphics7CGFloat8animatedSb8durationSd7optionsVSC22UIViewAnimationOptions_T_U_FT_T_ + 39 41 trustedfamily-ios 0x0000000101e572d7 _TTRXFo___XFdCb___ + 39 42 UIKit 0x0000000105af13da +[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 572 43 UIKit 0x0000000105af18dd +[UIView(UIViewAnimationWithBlocks) animateWithDuration:delay:options:animations:completion:] + 99 44 trustedfamily-ios 0x0000000101fe3b7f _TFC17trustedfamily_ios32ConversationDetailViewController28changeBottomLayoutConstraintfT2toV12CoreGraphics7CGFloat8animatedSb8durationSd7optionsVSC22UIViewAnimationOptions_T_ + 943 45 trustedfamily-ios 0x0000000101fe3e1f _TToFC17trustedfamily_ios32ConversationDetailViewController28changeBottomLayoutConstraintfT2toV12CoreGraphics7CGFloat8animatedSb8durationSd7optionsVSC22UIViewAnimationOptions_T_ + 79 46 trustedfamily-ios 0x0000000101fe30e6 _TFC17trustedfamily_ios32ConversationDetailViewController23keyboardWillChangeFramefV10Foundation12NotificationT_ + 2278 47 trustedfamily-ios 0x0000000101fe3237 _TToFC17trustedfamily_ios32ConversationDetailViewController23keyboardWillChangeFramefV10Foundation12NotificationT_ + 71 48 CoreFoundation 0x00000001044c9c2c __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12 49 CoreFoundation 0x00000001044c9b29 _CFXRegistrationPost + 425 50 CoreFoundation 0x00000001044c9892 ___CFXNotificationPost_block_invoke + 50 51 CoreFoundation 0x000000010448d102 -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1826 52 CoreFoundation 0x000000010448c261 _CFXNotificationPost + 673 53 Foundation 0x00000001030b6ca4 -[NSNotificationCenter postNotificationName:object:userInfo:] + 66 54 UIKit 0x000000010649ce05 -[UIInputWindowController postStartNotifications:withInfo:] + 225 55 UIKit 0x000000010649f0af __77-[UIInputWindowController moveFromPlacement:toPlacement:starting:completion:]_block_invoke.871 + 381 56 UIKit 0x0000000105af13da +[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 572 57 UIKit 0x0000000105af1853 +[UIView(UIViewAnimationWithBlocks) _animateWithDuration:delay:options:animations:start:completion:] + 116 58 UIKit 0x000000010649eacb -[UIInputWindowController moveFromPlacement:toPlacement:starting:completion:] + 1503 59 UIKit 0x00000001064a6d5e __43-[UIInputWindowController setInputViewSet:]_block_invoke.1318 + 97 60 UIKit 0x000000010649a59a -[UIInputWindowController performOperations:withTemplateNotificationInfo:] + 46 61 UIKit 0x00000001064a68ea -[UIInputWindowController setInputViewSet:] + 1753 62 UIKit 0x000000010649e14c -[UIInputWindowController performOperations:withAnimationStyle:] + 50 63 UIKit 0x0000000106114a8a -[UIPeripheralHost(UIKitInternal) setInputViews:animationStyle:] + 1505 64 UIKit 0x0000000106115c4b -[UIPeripheralHost(UIKitInternal) _preserveInputViewsWithId:animated:reset:] + 499 65 UIKit 0x0000000105bec35d -[UIViewController _presentViewController:modalSourceViewController:presentationController:animationController:interactionController:completion:] + 1145 66 UIKit 0x0000000105bedfae -[UIViewController _presentViewController:withAnimationController:completion:] + 4660 67 CoreFoundation 0x00000001044b2c6c __invoking___ + 140 68 CoreFoundation 0x00000001044b2b40 -[NSInvocation invoke] + 320 69 UIKit 0x0000000105bd1633 -[_UIDelayedPresentationContext finishDelayedPresentation:] + 230 70 UIKit 0x0000000105be9416 -[UIViewController _endDelayingPresentation] + 93 71 CoreFoundation 0x00000001044b2c6c __invoking___ + 140 72 CoreFoundation 0x00000001044b2b40 -[NSInvocation invoke] + 320 73 FrontBoardServices 0x000000010a1f25f6 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 24 74 FrontBoardServices 0x000000010a1f246d -[FBSSerialQueue _performNext] + 186 75 FrontBoardServices 0x000000010a1cb360 -[FBSWorkspace synchronizeSystemAnimationFencesWithCleanUpBlock:] + 1549 76 UIKit 0x0000000105a311d4 -[UIApplication _synchronizeSystemAnimationFencesWithSpinCleanUpBlock:] + 543 77 UIKit 0x0000000105ab22cd __realPreCommitHandler_block_invoke + 395 78 QuartzCore 0x000000010575532c _ZNK2CA11Transaction5Fence13run_callbacksEv + 40 79 QuartzCore 0x0000000105727f7c _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 528 80 QuartzCore 0x0000000105754130 _ZN2CA11Transaction6commitEv + 468 81 QuartzCore 0x0000000105754b37 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 115 82 CoreFoundation 0x00000001044d0717 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23 83 CoreFoundation 0x00000001044d0687 __CFRunLoopDoObservers + 391 84 CoreFoundation 0x00000001044b5720 __CFRunLoopRun + 1200 85 CoreFoundation 0x00000001044b5016 CFRunLoopRunSpecific + 406 86 GraphicsServices 0x000000010a9eda24 GSEventRunModal + 62 87 UIKit 0x0000000105a38134 UIApplicationMain + 159 88 trustedfamily-ios 0x0000000101ff6837 main + 55 89 libdyld.dylib 0x000000010894465d start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException
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13
  • 2
    post tableviewcell code as well Commented Sep 5, 2017 at 13:44
  • @suhit i have added more code, please see my edits. Commented Sep 5, 2017 at 14:10
  • 2
    Could you post the trace from the crash log? Commented Sep 5, 2017 at 14:21
  • @Bocaxica "keyboard frame changes" you mean on device rotation? Commented Sep 5, 2017 at 15:08
  • 1
    I've made an answer on a similar one. https://stackoverflow.com/a/52751998/2794052 Maybe it could help. Commented Oct 11, 2018 at 4:43

2 Answers 2

Reset to default
4

Try to make your html convert in NSAttributedString inside

DispatchQueue.main.async {

}

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2 Comments

Thanks, the problem doesn't appear anymore in my project, so I don't remember how I solved or worked around it. I am pretty sure it all ran on the main thread though.
@Bocaxica I thought the same
0

I'm seeing this crash in a very similar situation in the field but can't reproduce it myself.

Let's try this and see if it helps:

guard UIApplication.shared.applicationState == .active else { return NSAttributedString() }
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