如何扩展NSTextStorage？

Question

根据文档，我尝试将NSTextStorage子类并在文本视图中使用：

/*
 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;

*/

因此，我尝试使用委托来处理所有具有相同功能的所需事件：

@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

无论我作为代表使用什么: NSTextStorage或NSMutableAttributedString，结果都是一样的：

未指明的异常被引发* NSRunStorage，_NSBlockNumberForIndex()：索引(18446744073709551615)超出数组边界(0) *终止应用程序，原因：‘* NSRunStorage，_NSBlockNumberForIndex()：索引(18446744073709551615)超出数组界限(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:]

当我试图打电话时，终止开始

[textView insertText:@"123"];

但是在标准的NSTextStorage版本中，所有这些都能正常工作。

我需要做些什么来扩展这门课？

Answer 1

除了需要实现的NSAttributedString原语方法之外，我相信您还需要在重写replaceCharactersInRange:withString:和setAttributes:range:的过程中调用edited:range:changeInLength:。

类似于：

- (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。您在问题中引用的关于只需要覆盖2个NSMutableAttributedString原语的注释意味着您不必覆盖其他NSMutableAttributedString原语。

您仍然必须重写NSAttributedString超类的原语。这意味着您需要实现-attributesAtIndex:effectiveRange:、-length和-string。我注意到您确实包括了-string的一个实现，所以剩下的两个应该这样做。

如果你加上：

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

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

..。希望它能解决这个问题。