如何扩展NSTextStorage？

Question

根据文档，我尝试子类化NSTextStorage并在文本视图中使用它：

/*
 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;

*/

所以我尝试使用delegate来处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

无论我使用什么作为委托：NSTextStorage或NSMutableAttributedString，结果都是一样的：

引发了未捕获的异常* NSRunStorage，_ NSBlockNumberForIndex（）：index（18446744073709551615）超出数组边界（0）*由于未捕获的异常'NSRangeException'终止应用程序，原因：'*** NSRunStorage，_ NSBlockNumberForIndex（）：index（18446744073709551615）超出数组边界（0）'

堆栈跟踪：

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:]

我尝试打电话时终止开始

[textView insertText:@"123"];

但是在标准的NSTextStorage版本中，一切正常。

我需要做些什么来扩展这个类？

Answer 1

除了需要实现的NSAttributedString原始方法之外，我相信你还需要调用edited:range:changeInLength:在replaceCharactersInRange:withString:和setAttributes:range:覆盖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文档在这方面有点模糊。 您在问题中引用的注释，只需要覆盖2个NSMutableAttributedString原语只意味着您不必重写其他NSMutableAttributedString原语。

您仍然必须覆盖NSAttributedString超类的基元。 这意味着您需要实现-attributesAtIndex:effectiveRange: -length和-string 。 我注意到你确实包含了-string的实现，所以剩下的两个应该这样做。

如果你添加：

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

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

...然后希望它能解决这个问题。