UILable addAttributes 根据html图片内容进行高度设置

1.设置label的html图片

-(NSMutableAttributedString *)setAttributedString:(NSString *)str
{
    //如果有换行，把\n替换成

    //如果有需要把换行加上
    str = [str stringByReplacingOccurrencesOfString:@"\n" withString:@"
"];
    //设置HTML图片的宽度
    str = [NSString stringWithFormat:@"%@",[UIScreen mainScreen].bounds.size.width-28,str];
    NSMutableAttributedString *htmlString =[[NSMutableAttributedString alloc] initWithData:[str dataUsingEncoding:NSUTF8StringEncoding] options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute:[NSNumber numberWithInt:NSUTF8StringEncoding]} documentAttributes:NULL error:nil];
    //设置富文本字的大小
    [htmlString addAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:14]} range:NSMakeRange(0, htmlString.length)];
    //设置行间距
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [htmlString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [htmlString length])];

    return htmlString;
}

2.设置html图片的高度
计算出来的 height 正好是排版后的高度大小，是 CGFloat 类型，在是在我们设置UIlabel/Cell 高度时，可能存在四舍五入等，最后存在的一点点误差使得 UILabel 显示不全，可能出现缺少一行，上下空白太多等情况；

解决方案：为了确保布局按照我们计算的数据来，可以使用ceil函数对计算的 Size 取整，再加1，确保 UILabel按照计算的高度完好的显示出来； 或者使用方法CGRectIntegral(CGRect rect) 对计算的 Rect 取整，在加1;

-(CGFloat )getHTMLHeightByStr:(NSString *)str
{
    str = [str stringByReplacingOccurrencesOfString:@"\n" withString:@"
"];
    str = [NSString stringWithFormat:@"%@",[UIScreen mainScreen].bounds.size.width,str];

    NSMutableAttributedString *htmlString =[[NSMutableAttributedString alloc] initWithData:[str dataUsingEncoding:NSUTF8StringEncoding] options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute:[NSNumber numberWithInt:NSUTF8StringEncoding]} documentAttributes:NULL error:nil];
    [htmlString addAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:14]} range:NSMakeRange(0, htmlString.length)];
    //设置行间距
    NSMutableParagraphStyle *paragraphStyle1 = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle1 setLineSpacing:5];
    [htmlString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle1 range:NSMakeRange(0, [htmlString length])];

//    CGSize contextSize = [htmlString boundingRectWithSize:(CGSize){[UIScreen mainScreen].bounds.size.width-28, CGFLOAT_MAX} options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading context:nil].size;
    CGSize labelSize = [_detailLab sizeThatFits:CGSizeMake([UIScreen mainScreen].bounds.size.width-28, MAXFLOAT)];
    CGFloat height = ceil(labelSize.height) + 1;
    return height;
}