如何在用户滚动时更新NSTextView(不会崩溃)

Question

我正在使用NSTextView来显示长搜索的结果,其中添加了行,因为它们是由后台线程使用的

[self performSelectorOnMainThread: @selector(addMatch:) 
      withObject:options waitUntilDone:TRUE];

作为我的更新程序

-(void)addMatch:(NSDictionary*)options{
 ...
 NSTextStorage* store = [textView textStorage];
 [store beginEditing];
 [store appendAttributedString:text];
  ...
 [store endEditing];
}

这样可以正常工作,直到用户在更新时滚动匹配,此时会出现异常

- [NSLayoutManager _fillLayoutHoleForCharacterRange:desiredNumberOfLines:isSoft:]***在textStorage编辑时尝试布局.在textStorage编辑时使layoutManager进行布局是无效的(即textStorage已经发送了一个没有匹配的endEditing的beginEditing消息.)

在布局调用中:

    0   CoreFoundation                      0x00007fff92ea364c __exceptionPreprocess + 172
    1   libobjc.A.dylib                     0x00007fff8acd16de objc_exception_throw + 43
    2   CoreFoundation                      0x00007fff92ea34fd +[NSException raise:format:] + 205
    3   UIFoundation                        0x00007fff8fe4fbc1 -[NSLayoutManager(NSPrivate) _fillLayoutHoleForCharacterRange:desiredNumberOfLines:isSoft:] + 641
    4   UIFoundation                        0x00007fff8fe5970c _NSFastFillAllLayoutHolesForGlyphRange + 1493
    5   UIFoundation                        0x00007fff8fda8821 -[NSLayoutManager lineFragmentRectForGlyphAtIndex:effectiveRange:] + 39
    6   AppKit                              0x00007fff8ef3cb02 -[NSTextView _extendedGlyphRangeForRange:maxGlyphIndex:drawingToScreen:] + 478
    7   AppKit                              0x00007fff8ef3ba97 -[NSTextView drawRect:] + 1832
    8   AppKit                              0x00007fff8eed9a09 -[NSView(NSInternal) _recursive:displayRectIgnoringOpacity:inGraphicsContext:CGContext:topView:shouldChangeFontReferenceColor:] + 1186
    9   AppKit                              0x00007fff8eed9458 __46-[NSView(NSLayerKitGlue) drawLayer:inContext:]_block_invoke + 218
    10  AppKit                              0x00007fff8eed91f1 -[NSView(NSLayerKitGlue) _drawViewBackingLayer:inContext:drawingHandler:] + 2407
    11  AppKit                              0x00007fff8eed8873 -[NSView(NSLayerKitGlue) drawLayer:inContext:] + 108
    12  AppKit                              0x00007fff8efaafd2 -[NSTextView drawLayer:inContext:] + 179
    13  AppKit                              0x00007fff8ef22f76 -[_NSBackingLayerContents drawLayer:inContext:] + 145
    14  QuartzCore                          0x00007fff9337c177 -[CALayer drawInContext:] + 119
    15  AppKit                              0x00007fff8ef22aae -[_NSTiledLayer drawTile:inContext:] + 625
    16  AppKit                              0x00007fff8ef227df -[_NSTiledLayerContents drawLayer:inContext:] + 169
    17  QuartzCore                          0x00007fff9337c177 -[CALayer drawInContext:] + 119
    18  AppKit                              0x00007fff8f6efd64 -[NSTileLayer drawInContext:] + 169
    19  QuartzCore                          0x00007fff9337b153 CABackingStoreUpdate_ + 3306
    20  QuartzCore                          0x00007fff9337a463 ___ZN2CA5Layer8display_Ev_block_invoke + 59
    21  QuartzCore                          0x00007fff9337a41f x_blame_allocations + 81
    22  QuartzCore                          0x00007fff93379f1c _ZN2CA5Layer8display_Ev + 1546
    23  AppKit                              0x00007fff8ef226ed -[NSTileLayer display] + 119
    24  AppKit                              0x00007fff8ef1ec34 -[_NSTiledLayerContents update:] + 5688
    25  AppKit                              0x00007fff8ef1d337 -[_NSTiledLayer display] + 375
    26  QuartzCore                          0x00007fff93379641 _ZN2CA5Layer17display_if_neededEPNS_11TransactionE + 603
    27  QuartzCore                          0x00007fff93378d7d _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 35
    28  QuartzCore                          0x00007fff9337850e _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 242
    29  QuartzCore                          0x00007fff93378164 _ZN2CA11Transaction6commitEv + 390
    30  QuartzCore                          0x00007fff93388f55 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 71
    31  CoreFoundation                      0x00007fff92dc0d87 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    32  CoreFoundation                      0x00007fff92dc0ce0 __CFRunLoopDoObservers + 368
    33  CoreFoundation                      0x00007fff92db2f1a __CFRunLoopRun + 1178
    34  CoreFoundation                      0x00007fff92db2838 CFRunLoopRunSpecific + 296
    35  UIFoundation                        0x00007fff8fdfe744 -[NSHTMLReader _loadUsingWebKit] + 2097
    36  UIFoundation                        0x00007fff8fdffb55 -[NSHTMLReader attributedString] + 22
    37  UIFoundation                        0x00007fff8fe12cca _NSReadAttributedStringFromURLOrData + 10543
    38  UIFoundation                        0x00007fff8fe10306 -[NSAttributedString(NSAttributedStringUIFoundationAdditions) initWithData:options:documentAttributes:error:] + 115

有什么不对,假设一切都在beginEditing和endEditing之间？

Answer 1

从堆栈跟踪(未完成),它看起来像一个运行循环源在不合时宜的时刻触发.

NSAttributedString使用WebKit来解析HTML.WebKit有时会运行运行循环.对于一般情况,可能需要从网络获取资源才能正确呈现.由于这需要时间,因此它会运行运行循环以等待结果并同时处理其他事情.

其中一个运行循环源似乎是一个核心动画源,可以在某些动画中执行下一步(可能是滚动文本视图).

你没有显示beginEditing和之间的所有代码endEditing.我怀疑你已经构建了一个NSAttributedStringHTML或从这两个地方之间的URL中获取的数据.这允许Core Animation运行循环源触发.这要求绘制文本视图,要求其布局管理器布置文本.这发生在beginEditing之前但之前endEditing,这是异常的原因.

因此,尝试重新排序代码以构建所有NSAttributedStrings beginEditing.

并提交Apple的错误.在我看来,当NSAttributeString使用WebKit呈现HTML时,它需要使WebKit使用私有运行循环模式,因此没有其他源可以触发.他们可能更喜欢不同的解决方案,但错误是真实的.