我遇到一个状况，其中 try NSAttributedString(data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil) 会导致应用程序崩溃。
控制台上显示如下信息:
Assertion failure in void _prepareForCAFlush(UIApplication *__strong)()
该函数被调用于一个 extension String 中。
当我在控制台上输入 'po' 值时:
(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;
}
这个字符串存在于一个在UITableViewCell中显示的标签中。
当“键盘框架改变”时，函数会崩溃。iOS会重新绘制表格单元格，导致其内容被重新绘制。
由于崩溃发生在主线程上，因此该函数是在主线程上调用的。
可能导致此崩溃的原因是什么，我该如何解决？
编辑：表视图单元格代码
UITableViewDataSource 生成单元格：
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
}
Cell的实现：
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()
}
}
}
创建纯属性字符串的函数会对HTML进行一些样式上的添加（这是因为通过API传入的内容需要进行一些修改）。
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()
}
控制台崩溃输出：
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
reloadData()函数调用移动到viewDidAppear()中，从而允许HTML转换为字符串在主线程中进行。这解决了我的问题。希望它也能帮到你。 - Ayazmon