highlight string inside attributed string

gistfile1.m

- (NSAttributedString *)attributedStringWithString:(NSString *)string highlightedwithOccurencesOfString:(NSString *)stringToHighlight inColor:(DTColor *)color
{
  // build an attributed string to start with
	
	// font
	DTCoreTextFontDescriptor *fontDesc = [[DTCoreTextFontDescriptor alloc] init];
	fontDesc.fontFamily = @"Helvetica";
	fontDesc.pointSize = 20;
	
	// paragraph style
	DTCoreTextParagraphStyle *paraStyle = [DTCoreTextParagraphStyle defaultParagraphStyle];
	
	// convert to CT objects
	CTFontRef font = [fontDesc newMatchingFont];
	CTParagraphStyleRef para = [paraStyle createCTParagraphStyle];
			
	NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:CFBridgingRelease(para), (id)kCTParagraphStyleAttributeName, CFBridgingRelease(font), (id)kCTFontAttributeName, nil];
	
	// construct base string
	NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:string attributes:attributes];
	
	// find first occurrence of search string in source string
	NSRange range = [string rangeOfString:stringToHighlight];
	
	while(range.location != NSNotFound)
	{
		// highlight this range
		[attributedString addAttribute:DTBackgroundColorAttribute value:(id)[color CGColor] range:range];
		
		// find next
		range = [string rangeOfString:stringToHighlight options:0 range:NSMakeRange(range.location + 1, [string length] - range.location - 1)];
	}
	
	return attributedString;
}