ios - 如果计算带有自定义表情的attributedString的size

Question

    CGSize textBlockMinSize = {TEXTLABEL_MAX_WIDTH, CGFLOAT_MAX};
    CGSize retSize;

    NSAttributedString *attributedString = _textLabel.attributedText;
    
    CGRect boundingRect = [attributedString boundingRectWithSize:textBlockMinSize options:NSStringDrawingUsesLineFragmentOrigin context:nil];
    retSize = boundingRect.size;

我用这个办法计算出来的size不准，应该怎么计算带有自定义表情的attributedString的size？不是emoji

表情格式是[中文]