TTTAttributedLabelUILabel 改进版

TTTAttributedLabel 是 UILable 的改进，支持 NSAttributedStrings。

示例代码：

TTTAttributedLabel *label = [[[TTTAttributedLabel alloc] initWithFrame:CGRectZero] autorelease];
label.font = [UIFont systemFontOfSize:14];
label.textColor = [UIColor darkGrayColor];
label.lineBreakMode = UILineBreakModeWordWrap;
label.numberOfLines = 0;

NSString *text = @"Lorem ipsum dolar sit amet";
[label setText:text afterInheritingLabelAttributesAndConfiguringWithBlock:^ NSAttributedString *(NSMutableAttributedString *mutableAttributedString) {
  NSRange boldRange = [[mutableAttributedString string] rangeOfString:@"ipsum dolar" options:NSCaseInsensitiveSearch];
  NSRange strikeRange = [[mutableAttributedString string] rangeOfString:@"sit amet" options:NSCaseInsensitiveSearch];

  // Core Text APIs use C functions without a direct bridge to UIFont. See Apple's "Core Text Programming Guide" to learn how to configure string attributes.
  UIFont *boldSystemFont = [UIFont boldSystemFontOfSize:14]; 
    CTFontRef font = CTFontCreateWithName((CFStringRef)boldSystemFont.fontName, boldSystemFont.pointSize, NULL);
    if (font) {
      [mutableAttributedString addAttribute:(NSString *)kCTFontAttributeName value:(id)font range:boldRange];
      [mutableAttributedString addAttribute:@"TTTCustomStrikeOut" value:[NSNumber numberWithBool:YES] range:strikeRange];
      CFRelease(font);
    }

    return mutableAttributedString;
}];