计算YYLabel内容富文本的高度

计算YYLabel内容富文本(带行间距)attributeStr的高度，假设行间距间距是5，走的弯路：

一、根据内容求高度

/// 带有行间距求高度 假如是行间距是5
- (CGRect)boundsWithFont:(UIFont *)font text:(NSString *)text needWidth:(CGFloat)needWidth lineSpacing:(CGFloat )lineSpacing
{ 
    NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:text];
    // 样式
    NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
    style.lineSpacing = lineSpacing; // 行间距
    style.lineBreakMode = NSLineBreakByWordWrapping;
   // 样式
    [attributeString addAttribute:NSParagraphStyleAttributeName value:style range:NSMakeRange(0, text.length)];
   // 文字大小
    [attributeString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:textFontValue15] range:NSMakeRange(0, text.length)];
    
    NSStringDrawingOptions options = NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading;
    CGRect rect = [attributeString boundingRectWithSize:CGSizeMake(needWidth, CGFLOAT_MAX) options:options context:nil];
    
    return rect;
    
}

二、 YYLabel赋值NSString->NSAttributedString（带行间距）

/// 设置行间距的NSAttributedString赋值给YYLabel
- (NSAttributedString *)matchesAttributedString:(NSString *)str{
    NSMutableAttributedString *attrStr = [[NSMutableAttributedString alloc] initWithString:str];

    // 间距
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle setLineSpacing:5.0]; // 行间距假如是5
    paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
    [attrStr addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [str length])];
    
    [attrStr addAttribute:NSForegroundColorAttributeName value:UIColorFromHEX(0x242831) range:NSMakeRange(0, attrStr.length)];
    [attrStr addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:textFontValue15] range:NSMakeRange(0, attrStr.length)];

   
    return attrStr;
}

当文本比较多的时候展示出的空白比较多，根据观察是展示的行间距小于5.0，所以整体偏中聚集，上下留白较多。但是对于UILabel是没有问题的。

三、3.1 对于YYLabel正确的做法是如下所示：

     // 计算文本尺寸YYTextLayout
     CGSize maxSize = CGSizeMake(fixWidth, MAXFLOAT);
     
     YYTextLayout *layout = [YYTextLayout layoutWithContainerSize:maxSize text:self.contentLbl.attributedText];
     self.contentLbl.textLayout = layout;
     CGFloat introHeight = layout.textBoundingSize.height;
        
     self.contentLbl.width = maxSize.width;
     // 记录真正的正确高度
     contentH = introHeight; 

3.2 不借助控件求高度：

CGSize maxSize = CGSizeMake(fixWidth, MAXFLOAT);
        
//计算文本尺寸
YYTextLayout *layout = [YYTextLayout layoutWithContainerSize:maxSize text:[self matchesAttributedString:@"普通文本内容"]];
CGFloat introHeight = layout.textBoundingSize.height;
contentH = introHeight; // 高度

注：matchesAttributedString:自定义的方法，NSString->NSAttributedString见上文