如何在NSString中获取特定字符的所有NSRange？

Question

我有两个NSStrings:orgText和searchLetter.
我想orgText用红色突出显示searchLetter的每一个匹配项.
我怎样才能得到NSRange所有出现的searchLetter？
例如:

suppose: orgText = "abcahaiapaoiuiapplma"
         searchLetter = "a".

我想高亮显示红色"abcahaiapaoiuiapplma"中的所有"a"事件.
谢谢.

Answer 1

我为我的项目编写了这个方法 - 带有高亮显示的SUITextView:

- (NSMutableAttributedString*) setColor:(UIColor*)color word:(NSString*)word inText:(NSMutableAttributedString*)mutableAttributedString {

    NSUInteger count = 0, length = [mutableAttributedString length];
    NSRange range = NSMakeRange(0, length);

    while(range.location != NSNotFound)
    {
        range = [[mutableAttributedString string] rangeOfString:word options:0 range:range];
        if(range.location != NSNotFound) {
            [mutableAttributedString setTextColor:color range:NSMakeRange(range.location, [word length])];
            range = NSMakeRange(range.location + range.length, length - (range.location + range.length));
            count++; 
        }
    }

    return mutableAttributedString;
}

在我的NSMutableAttributedString类别中:

- (void) setTextColor:(UIColor*)color range:(NSRange)range {
    // kCTForegroundColorAttributeName
    [self removeAttribute:(NSString*)kCTForegroundColorAttributeName range:range]; // Work around for Apple leak
    [self addAttribute:(NSString*)kCTForegroundColorAttributeName value:(id)color.CGColor range:range];
}

Answer 2

我没有看到任何正则表达式的解决方案,所以我创建了一个优雅的解决方案,它可能对将来的某个人有用.

- (BOOL)highlightString:(NSString *)string inText:(NSMutableAttributedString *)attributedString withColour:(UIColor *)color {
    NSError *_error;
    NSRegularExpression *_regexp = [NSRegularExpression regularExpressionWithPattern:string options:NSRegularExpressionCaseInsensitive error:&_error];
    if (_error == nil) {
        [_regexp enumerateMatchesInString:attributedString.string options:NSMatchingReportProgress range:NSMakeRange(0, attributedString.string.length) usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop) {
            if (result.numberOfRanges > 0) {
                for (int i = 0; i < result.numberOfRanges; i++) {
                    [attributedString addAttribute:NSBackgroundColorAttributeName value:color range:[result rangeAtIndex:i]];
                }
            }
        }];
        return TRUE;
    } else {
        return FALSE;
    }
}