// 生成AttributeString
-(NSAttributedString *)attributeWithLineSpace:(CGFloat)lineSpace font:(UIFont *)font color:(UIColor *)color withText:(NSString *)text{
    NSParameterAssert(font && color);
    if (text.length == 0) return nil;
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.lineSpacing = lineSpace;  //设置行间距
    paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
    paragraphStyle.alignment = NSTextAlignmentLeft;
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:text attributes:@{NSFontAttributeName:font,NSForegroundColorAttributeName:color}];
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [text length])];
    return [attributedString copy];
}

// 根据AttributeString计算高度
 NSAttributedString *explaintAtt = [self attributeWithLineSpace:8 font:[UIFont pf_MediumFontOfSize:14] color:HEX_RGBA(0x333331, 1) withText:_newsModel.explain];
CGSize size =  [explaintAtt boundingRectWithSize:CGSizeMake(SCREEN_WIDTH() - 44 - 33 , MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading context:nil].size;
// 注意这里取整加1
 CGFloat height= ceil(size.height) + 1;