How to get all NSRange of a particular character in a NSString?

Question

I have two NSStrings: orgText and searchLetter.
I want to highlight every occurrences of the searchLetter in the orgText with a re

Answer 1

I'm not seeing any solution with regular expression, so I've created an elegant one, it may be useful for someone in the future.

- (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;
    }
}