想模仿淘宝的评论那样添加图片然后添加按钮向后移，利用flex布局，当添加两张向后移了，添加三张的时候刚好一行，图片都跑下去了，添加框留在上面了。
页面代码

                <View className="choimgs">
              {imagesList.map((item, index) => (
                <View key={index} className="imgs">
                  <Image src={item} className="imgitem"></Image>
                </View>
              ))}
              <View className="dottdiv" onClick={this.chooseimg}>
                +
              </View>
              

css代码

         .choimgs {
            margin-top: 30px;
            display: flex;
            justify-content: space-between;
            flex-wrap: wrap-reverse;
            .dottdiv {
                width: 200px;
                height: 200px;
                border: 2px dashed lightblue;
                text-align: center;
                line-height:200px;
                font-size: 150px;
                font-weight: 200;
                color: #ccc;
            }
            .imgs {
                .imgitem {
                    width: 200px;
                    height: 200px;
                }
            }
        }
        .choimgs::after {
            content: "";
            flex: auto;
        }