ios 使用富文本加载HTML

富文本设置

1. \n替换
2. 图片宽度设置
3. 行间距设置

-(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,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:16]} range:NSMakeRange(0, htmlString.length)];
//设置行间距
 NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle1 setLineSpacing:5];
 [htmlString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [htmlString length])];

    return htmlString;
}

获取富文本的高度

//计算html字符串高度
-(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:16]} 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), CGFLOAT_MAX} options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading context:nil].size;
    return contextSize.height ;
    
}