create NSAttributeString using RE

iOS_NSAttributeString.m

//center
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle setAlignment:NSTextAlignmentCenter];
//origin string
NSString *detail = [NSString stringWithFormat:@"%zd more people .....", [RemoteConfigUtil moreRecentOnlineTotalNumber]];
//attributed string
NSMutableAttributedString *attributedDetail = [[NSMutableAttributedString alloc] initWithString:detail 
                                                attributes:@{NSParagraphStyleAttributeName:paragraphStyle,
                                                             NSFontAttributeName:[UIFont systemFontOfSize:16], 
                                                             NSForegroundColorAttributeName:RGBCOLOR_HEX(0x333E55)}];
NSRange boldRange = [detail rangeOfString:@"\\d+" options:NSRegularExpressionSearch|NSCaseInsensitiveSearch];
if (boldRange.location != NSNotFound) {
    [attributedDetail addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:16] range:boldRange];
}

//UILabel的numberOfLines对它的attributedText属性也有作用