//设置lab的行间距

                NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:_doubletStr];

                NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];

                [paragraphStyle setLineSpacing:10];//调整行间距

                [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, _doubletStr.length)];

                _resultLab.attributedText = attributedString;

 //计算label带行间距的行高

                CGFloat labelHeight = [_resultLab sizeThatFits:CGSizeMake(_resultLab.frame.size.width, MAXFLOAT)].height;

                

    //label有多少行

                NSNumber *count = @((labelHeight) / _resultLab.font.lineHeight);

                NSLog(@"共 %td 行", [count integerValue]);