我正在尝试制作一个irc客户端。我保留一个 NSTextView 对象，并且我有一个包含 NSTextStorage 对象的容器类。每次用户单击“频道按钮”时，我都会使用 NSTextView 的 layoutManager 替换 NSTextStorage 对象。存储的文本采用 NSAttributedString 的形式，因为我想要不同颜色的部分文本。
我在 NSTextStorage 中存储 NSAttributedString 的方式是我从容器对象中获取指针并在其上使用 appendAttributedString。
而且我在 NSLog 中遇到了一个未捕获的异常并且没有中断。你能帮我找出问题所在吗？
2015-09-14 08:25:49.776 ircX[3248:128903] *** -[NSConcreteTextStorage attributesAtIndex:effectiveRange:]: Range or index out of bounds
2015-09-14 08:25:49.780 ircX[3248:128903] (
0 CoreFoundation 0x00007fff9974503c __exceptionPreprocess + 172
1 libobjc.A.dylib 0x00007fff99c0176e objc_exception_throw + 43
2 CoreFoundation 0x00007fff99744eed +[NSException raise:format:] + 205
3 UIFoundation 0x00007fff939c7d77 -[NSConcreteTextStorage attributesAtIndex:effectiveRange:] + 127
4 AppKit 0x00007fff94e05ffc -[NSTextView(NSSharing) setSelectedRanges:affinity:stillSelecting:] + 2525
5 UIFoundation 0x00007fff939a53af -[NSLayoutManager textStorage:edited:range:changeInLength:invalidatedRange:] + 423
6 UIFoundation 0x00007fff939c7291 -[NSTextStorage _notifyEdited:range:changeInLength:invalidatedRange:] + 152
7 UIFoundation 0x00007fff939c6d93 -[NSTextStorage processEditing] + 198
8 UIFoundation 0x00007fff939c6c98 -[NSTextStorage edited:range:changeInLength:] + 312
9 Foundation 0x00007fff925935e3 -[NSConcreteMutableAttributedString replaceCharactersInRange:withAttributedString:] + 330
10 UIFoundation 0x00007fff939c87c1 __71-[NSConcreteTextStorage replaceCharactersInRange:withAttributedString:]_block_invoke + 52
11 UIFoundation 0x00007fff939c8703 -[NSConcreteTextStorage replaceCharactersInRange:withAttributedString:] + 136
12 ircX 0x000000010000b68b -[IRCWindow addData:] + 3371
13 ircX 0x000000010000195f -[ViewController updateTextView] + 527
14 Foundation 0x00007fff9259f953 __NSFireTimer + 95
15 CoreFoundation 0x00007fff996982e4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
16 CoreFoundation 0x00007fff99697f73 __CFRunLoopDoTimer + 1059
17 CoreFoundation 0x00007fff9970b53d __CFRunLoopDoTimers + 301
18 CoreFoundation 0x00007fff99653608 __CFRunLoopRun + 2024
19 CoreFoundation 0x00007fff99652bd8 CFRunLoopRunSpecific + 296
20 HIToolbox 0x00007fff962a956f RunCurrentEventLoopInMode + 235
21 HIToolbox 0x00007fff962a92ea ReceiveNextEventCommon + 431
22 HIToolbox 0x00007fff962a912b _BlockUntilNextEventMatchingListInModeWithFilter + 71
23 AppKit 0x00007fff94d6c8ab _DPSNextEvent + 978
24 AppKit 0x00007fff94d6be58 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 346
25 AppKit 0x00007fff94d61af3 -[NSApplication run] + 594
26 AppKit 0x00007fff94cde244 NSApplicationMain + 1832
27 ircX 0x00000001000020b2 main + 34
28 libdyld.dylib 0x00007fff8ec045c9 start + 1
)