TTTAttributedLabel crash when calculating size for some content

[robinspeijer]

Steps to reproduce:

• Browse any reddit content on iOS 13.3
• At some point, the app crashes with the following stacktrace:

Thread 1 Queue : com.apple.main-thread (serial)
#0	0x00000001b298dec4 in __pthread_kill ()
#1	0x00000001b28ad724 in pthread_kill$VARIANT$armv81 ()
#2	0x00000001b27fd844 in abort ()
#3	0x00000001b29567d4 in abort_message ()
#4	0x00000001b29569c4 in demangling_terminate_handler() ()
#5	0x00000001b28be258 in _objc_terminate() ()
#6	0x00000001b2963304 in std::__terminate(void (*)()) ()
#7	0x00000001b2962c58 in __cxxabiv1::failed_throw(__cxxabiv1::__cxa_exception*) ()
#8	0x00000001b2962c18 in __cxa_throw ()
#9	0x00000001b28be0d0 in objc_exception_throw ()
#10	0x00000001b2a9a5a8 in -[NSObject(NSObject) doesNotRecognizeSelector:] ()
#11	0x00000001b2b9aaf4 in ___forwarding___ ()
#12	0x00000001b2b9ca7c in _CF_forwarding_prep_0 ()
#13	0x00000001b3895b60 in TAttributes::HandleUnderlineAttribute(void const*, TAttributes::AttributeHandlerContext*) ()
#14	0x00000001b6135600 in -[NSAttributeDictionary __apply:context:] ()
#15	0x00000001b38951b0 in TAttributes::ParseAttributes(__CFDictionary const*, __CTFont const*, void const*&, TInlineVector<std::__1::function<void (TAttributes&)>, 30ul>&, std::__1::pair<bool, LigatureSetting>*) ()
#16	0x00000001b38949ec in TAttributes::ApplyFont(__CFDictionary const*, __CTFont const*, void const**) ()
#17	0x00000001b389482c in TAttributes::TAttributes(__CFDictionary const*) ()
#18	0x00000001b383e74c in TTypesetterAttrString::Initialize(__CFAttributedString const*) ()
#19	0x00000001b383e5c8 in TTypesetterAttrString::TTypesetterAttrString(__CFAttributedString const*, __CFDictionary const*) ()
#20	0x00000001b383a98c in TCFRef<CTFramesetterAttrString*> TCFBase_NEW<CTFramesetterAttrString, __CFAttributedString const*&>(__CFAttributedString const*&) ()
#21	0x00000001b383a8c4 in CTFramesetterCreateWithAttributedString ()
#22	0x00000001017af9c0 in -[TTTAttributedLabel framesetter] at /Users/robin/Development/Awkward/beam/TTTAttributedLabel/TTTAttributedLabel/TTTAttributedLabel.m:407
#23	0x00000001017b7d30 in -[TTTAttributedLabel sizeThatFits:] at /Users/robin/Development/Awkward/beam/TTTAttributedLabel/TTTAttributedLabel/TTTAttributedLabel.m:1333
#24	0x00000001017b7efc in -[TTTAttributedLabel intrinsicContentSize] at /Users/robin/Development/Awkward/beam/TTTAttributedLabel/TTTAttributedLabel/TTTAttributedLabel.m:1350
#25	0x00000001b6fc80d4 in -[UIView(UIConstraintBasedLayout) _generateContentSizeConstraints] ()
#26	0x00000001b6fc7dbc in -[UIView(UIConstraintBasedLayout) _updateContentSizeConstraints] ()
#27	0x00000001b6fd19bc in -[UIView(AdditionalLayoutSupport) _updateSystemConstraints] ()
#28	0x00000001b6fd0750 in -[UIView(AdditionalLayoutSupport) _sendUpdateConstraintsIfNecessaryForSecondPass:] ()
#29	0x00000001b6fd0c1c in -[UIView(AdditionalLayoutSupport) _updateConstraintsIfNeededCollectingViews:forSecondPass:] ()
#30	0x00000001b6fd0b00 in -[UIView(AdditionalLayoutSupport) _updateConstraintsIfNeededCollectingViews:forSecondPass:] ()
#31	0x00000001b2e6e06c in -[NSISEngine withBehaviors:performModifications:] ()
#32	0x00000001b6fd0e3c in -[UIView(AdditionalLayoutSupport) _recursiveUpdateConstraintsIfNeededCollectingViews:forSecondPass:] ()
#33	0x00000001b6fd0b00 in -[UIView(AdditionalLayoutSupport) _updateConstraintsIfNeededCollectingViews:forSecondPass:] ()
#34	0x00000001b6fd12f8 in __100-[UIView(AdditionalLayoutSupport) _updateConstraintsIfNeededWithViewForVariableChangeNotifications:]_block_invoke ()
#35	0x00000001b6fd0f30 in -[UIView(AdditionalLayoutSupport) _updateConstraintsIfNeededWithViewForVariableChangeNotifications:] ()
#36	0x00000001b6fcb8bc in -[UIView(AdditionalLayoutSupport) _systemLayoutSizeFittingSize:withHorizontalFittingPriority:verticalFittingPriority:hasIntentionallyCollapsedHeight:] ()
#37	0x00000001b6d7f574 in -[UITableViewCell systemLayoutSizeFittingSize:withHorizontalFittingPriority:verticalFittingPriority:] ()
#38	0x00000001b6df60d4 in -[UITableView _heightForCell:atIndexPath:] ()
#39	0x00000001b6dde428 in __53-[UITableView _configureCellForDisplay:forIndexPath:]_block_invoke ()
#40	0x00000001b7091e68 in +[UIView(Animation) performWithoutAnimation:] ()
#41	0x00000001b6ddd938 in -[UITableView _configureCellForDisplay:forIndexPath:] ()
#42	0x00000001b6deeca0 in -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] ()
#43	0x00000001b6dbc2c4 in -[UITableView _updateVisibleCellsNow:] ()
#44	0x00000001b6dcf3dc in -[UITableView _visibleCellsUsingPresentationValues:] ()
#45	0x00000001009c6e84 in StreamViewController.updateGifPlayingState() at /Users/robin/Development/Awkward/beam/Beam/UI/Subreddits/Posts Stream/StreamViewController.swift:890
#46	0x00000001009df8d8 in StreamViewController.scrollViewDidScroll(_:) at /Users/robin/Development/Awkward/beam/Beam/UI/Subreddits/Posts Stream/StreamViewController.swift:913
#47	0x00000001009dfda4 in @objc StreamViewController.scrollViewDidScroll(_:) ()
#48	0x00000001b702fc60 in -[UIScrollView _notifyDidScroll] ()
#49	0x00000001b6dbcff8 in -[UITableView _notifyDidScroll] ()
#50	0x00000001b7019e70 in -[UIScrollView setContentOffset:] ()
#51	0x00000001b6ddbafc in -[UITableView setContentOffset:] ()
#52	0x00000001b70195a0 in _UIScrollViewAdjustForOverlayInsetsChangeIfNecessary ()
#53	0x00000001b7034a3c in -[UIScrollView setSafeAreaInsets:] ()
#54	0x00000001b65e4658 in -[UIViewController _updateViewSafeAreaInsetsAndEagerlyUpdateContentScrollView:] ()
#55	0x00000001b65e4d9c in -[UIViewController _setContentOverlayInsets:andLeftMargin:rightMargin:] ()
#56	0x00000001b65e674c in __121-[UIViewController __updateContentOverlayInsetsWithOurRect:inBoundsOfAncestorViewController:viaImmediateChildOfAncestor:]_block_invoke ()
#57	0x00000001b65e6558 in -[UIViewController __updateContentOverlayInsetsWithOurRect:inBoundsOfAncestorViewController:viaImmediateChildOfAncestor:] ()
#58	0x00000001b65e57b0 in -[UIViewController _updateContentOverlayInsetsFromParentIfNecessary] ()
#59	0x00000001b65e5008 in -[UIViewController _updateContentOverlayInsetsForSelfAndChildren] ()
#60	0x00000001b65f1944 in -[UIViewController _updateLayoutForStatusBarAndInterfaceOrientation] ()
#61	0x00000001b65f64e4 in -[UIViewController viewDidMoveToWindow:shouldAppearOrDisappear:] ()
#62	0x00000001b70961a8 in -[UIView(Internal) _didMoveFromWindow:toWindow:] ()
#63	0x00000001b7095f88 in -[UIView(Internal) _didMoveFromWindow:toWindow:] ()
#64	0x00000001b708a334 in __45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke ()
#65	0x00000001b708a21c in -[UIView(Hierarchy) _postMovedFromSuperview:] ()
#66	0x00000001b7098b24 in -[UIView(Internal) _addSubview:positioned:relativeTo:] ()
#67	0x00000001b7058c88 in -[UINavigationTransitionView transition:fromView:toView:] ()
#68	0x00000001b6562290 in -[UINavigationController _startTransition:fromViewController:toViewController:] ()
#69	0x00000001b65626f4 in -[UINavigationController _startDeferredTransitionIfNeeded:] ()
#70	0x00000001b6563a34 in -[UINavigationController __viewWillLayoutSubviews] ()
#71	0x00000001b6546eb8 in -[UILayoutContainerView layoutSubviews] ()
#72	0x00000001b709f3d0 in -[UIView(CALayerDelegate) layoutSublayersOfLayer:] ()
#73	0x00000001b96027dc in -[CALayer layoutSublayers] ()
#74	0x00000001b9608958 in CA::Layer::layout_if_needed(CA::Transaction*) ()
#75	0x00000001b9613578 in CA::Layer::layout_and_display_if_needed(CA::Transaction*) ()
#76	0x00000001b955bf1c in CA::Context::commit_transaction(CA::Transaction*, double) ()
#77	0x00000001b9585c08 in CA::Transaction::commit() ()
#78	0x00000001b6c32b08 in _afterCACommitHandler ()
#79	0x00000001b2b13e68 in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ ()
#80	0x00000001b2b0ed54 in __CFRunLoopDoObservers ()
#81	0x00000001b2b0f320 in __CFRunLoopRun ()
#82	0x00000001b2b0eadc in CFRunLoopRunSpecific ()
#83	0x00000001bca94328 in GSEventRunModal ()
#84	0x00000001b6c09ae0 in UIApplicationMain ()
#85	0x00000001008897d8 in main at /Users/robin/Development/Awkward/beam/Beam/AppDelegate.swift:37
#86	0x00000001b2998360 in start ()

[robinspeijer]

This problem has to do with an unexpected value for NSUnderlineStyleAttributeName in the NSAttributedString in TTTAttributedLabel. Instead of a number, it was assigned an empty array value. With NSUnderlineStyle being an optionset in Swift, it didn't raise any suspicion.

This should be fixed by #34