如何擴展NSTextStorage？

Question

根據文檔，我嘗試子類化NSTextStorage並在文本視圖中使用它：

/*
 NSTextStorage is a semi-abstract subclass of NSMutableAttributedString. It
 implements change management (beginEditing/endEditing), verification of
 attributes, delegate handling, and layout management notification. The one
 aspect it does not implement is the actual attributed string storage --- this is
 left up to the subclassers, which need to override the two
 NSMutableAttributedString primitives:

 - (void)replaceCharactersInRange:(NSRange)range withString:(NSString *)str;
 - (void)setAttributes:(NSDictionary *)attrs range:(NSRange)range;

*/

所以我嘗試使用delegate來處理具有相同功能的所有需要​​的事件：

@implementation MyTextStorage

- (id) init {
    self = [super init];

    if (self != nil) {
        storage = [[NSMutableAttributedString alloc] init];
    }

    return self;
}

- (void) dealloc {
    [storage release];
    [super dealloc];
}

- (NSString *) string {
    return [storage string];
}

- (void) replaceCharactersInRange:(NSRange)range withString:(NSString *)str {
    [storage replaceCharactersInRange:range withString:str];
}

- (void)setAttributes:(NSDictionary *)attrs range:(NSRange)range {
    [storage setAttributes:attrs range:range];
}


@end

無論我使用什么作為委托：NSTextStorage或NSMutableAttributedString，結果都是一樣的：

引發了未捕獲的異常* NSRunStorage，_ NSBlockNumberForIndex（）：index（18446744073709551615）超出數組邊界（0）*由於未捕獲的異常'NSRangeException'終止應用程序，原因：'*** NSRunStorage，_ NSBlockNumberForIndex（）：index（18446744073709551615）超出數組邊界（0）'

堆棧跟蹤：

0   CoreFoundation                      0x00007fff840cd7b4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x00007fff885390f3 objc_exception_throw + 45
    2   CoreFoundation                      0x00007fff840cd5d7 +[NSException raise:format:arguments:] + 103
    3   CoreFoundation                      0x00007fff840cd564 +[NSException raise:format:] + 148
    4   AppKit                              0x00007fff86cc6288 _NSBlockNumberForIndex + 86
    5   AppKit                              0x00007fff86cc71d5 -[NSLayoutManager textContainerForGlyphAtIndex:effectiveRange:] + 364
    6   AppKit                              0x00007fff86d1f121 -[NSTextView(NSSharing) didChangeText] + 340
    7   AppKit                              0x00007fff86d44b68 -[NSTextView insertText:replacementRange:] + 2763
    8   CocoaCalculator                     0x0000000100002312 -[CalcTextView insertText:] + 65
    9   CocoaCalculator                     0x00000001000027ac -[CalcTextContainer initWithFrame:] + 1176
    10  AppKit                              0x00007fff86c23d44 -[NSCustomView nibInstantiate] + 646
    11  AppKit                              0x00007fff86b7be17 -[NSIBObjectData instantiateObject:] + 259
    12  AppKit                              0x00007fff86b7b202 -[NSIBObjectData nibInstantiateWithOwner:topLevelObjects:] + 336
    13  AppKit                              0x00007fff86b7988d loadNib + 226
    14  AppKit                              0x00007fff86b78d9a +[NSBundle(NSNibLoading) _loadNibFile:nameTable:withZone:ownerBundle:]

我嘗試打電話時終止開始

[textView insertText:@"123"];

但是在標准的NSTextStorage版本中，一切正常。

我需要做些什么來擴展這個類？

Answer 1

除了需要實現的NSAttributedString原始方法之外，我相信你還需要調用edited:range:changeInLength:在replaceCharactersInRange:withString:和setAttributes:range:覆蓋setAttributes:range: 。

就像是：

- (void) replaceCharactersInRange:(NSRange)range withString:(NSString *)str {
    [storage replaceCharactersInRange:range withString:str];
    [self edited:NSTextStorageEditedCharacters range:range changeInLength:[str length] - range.length];
}

- (void)setAttributes:(NSDictionary *)attrs range:(NSRange)range {
    [storage setAttributes:attrs range:range];
    [self edited:NSTextStorageEditedAttributes range:range changeInLength:0];
}

Answer 2

NSTextStorage文檔在這方面有點模糊。 您在問題中引用的注釋，只需要覆蓋2個NSMutableAttributedString原語只意味着您不必重寫其他NSMutableAttributedString原語。

您仍然必須覆蓋NSAttributedString超類的基元。 這意味着您需要實現-attributesAtIndex:effectiveRange: -length和-string 。 我注意到你確實包含了-string的實現，所以剩下的兩個應該這樣做。

如果你添加：

- (NSUInteger)length
{
     return [storage length];
}

- (NSDictionary *)attributesAtIndex:(NSUInteger)location effectiveRange:(NSRangePointer)range
{
      return [storage attributesAtIndex:location effectiveRange:range];
}

...然后希望它能解決這個問題。