通常我们会遇到ios手机不能下载文件的问题，那是因为苹果手机的拦截机制，这时我们只能通过别的方法来解决问题，我这里的解决方法是直接实现在线预览

1. pdf预览跟图片预览不同，pdf可能会有多张，而图片只有一张，使用图片预览的组件肯定是行不通的
2. 这里我使用的是一个vue-pdf的插件，这是一个使用起来容易上手的插件。首先我们需要在vue项目中引入它：

npm install --save vue-pdf

然后在展示pdf的页面引用

import pdf from ‘vue-pdf’

3. 要想让pdf实现手势缩放和移动，也需要导入插件，这里我使用的是AlloyFinger 超轻量级 Web 手势库，首先我们需要在vue项目引入它：

npm install alloyfinger

然后在main.js中导入

//Alloyfinger手势插件
import AlloyFinger from 'alloyfinger'
import AlloyFingerPlugin from 'alloyfinger/vue/alloy_finger_vue'

Vue.use(AlloyFingerPlugin,{
  AlloyFinger
})

html代码

<template>
 <div class="pdf-tab">
   <div
     class="btn-def btn-pre"
     @click.stop="prePage">上一页
   </div>
   <div
     class="btn-def btn-next"
     @click.stop="nextPage">下一页
   </div>
 </div>
 <div>{{pageNum}}/{{pageTotalNum}}</div>
 <div class="any-scroll-view">
   <div ref="body" :style="bodyStyle">
     <pdf
       id="pdfPreview"
       ref="pdf"
       :src="pdfUrl"
       :page="pageNum"
       :rotate="pageRotate"
       @password="password"
       @progress="loadedRatio = $event"
       @page-loaded="pageLoaded($event)"
       @num-pages="pageTotalNum=$event"
       @error="pdfError($event)"
       @link-clicked="page = $event">
     </pdf>
   </div>
 </div>
</div>
</template>

js代码和style代码
alloyfinger.js、transform.js、to.js引入的这三个js里封装了手势缩放移动、旋转的方法，可以去GitHub将源码挡下来，将这三个js复制到自己的static文件下，然后引用即可。点此进入GitHub

<script>
  import pdf from 'vue-pdf'
  import AlloyFinger from "../../../static/js/alloyfinger.js";
  import transform from "../../../static/js/transform.js";
  import To from "../../../static/js/to.js";

  export default {
    name: 'mistakesVoucher',
     props: {
        // 减速度, 单位px/s²
        acceleration: {
            type: Number,
            default: 3600
        }
    },
    data() {
      return {
        id: '',
        pdfUrl:'',// pdf文件地址
        pageNum:1,
        pageTotalNum:1,
        pageRotate:0,
        // 加载进度
        loadedRatio:0,
        curPageNum:0,
        transitionDuration: 300,
        goPath: '',             //将要去的界面
      };
    },
    beforeRouteEnter (to, from, next) { //监听从哪个页面过来
       let path = from.fullPath;
       next(vm => vm.setPath(path));
    },
    created(){
      this.getParams()
    },
    computed: {
        bodyStyle() {
            return {
                transitionDuration: `${this.transitionDuration}ms`,
                transform: `translate(${this.scrollLeft}px, ${
                    this.scrollTop
                }px)`
            };
        }
    },
    mounted() {
      this.getData();
    },
    methods: {
      setPath(path) {
        this.goPath = path.split("/")[1];
      },
      //返回键
      back() {
        this.$router.push({
          name: this.goPath,
          params: {
            id: this.id
          }
        })
      },
      getParams() {
       // 取到路由带过来的参数
       let routerParams = this.$route.params.id
       // 将数据放在当前组件的数据内
       this.id = routerParams
       this.pdfUrl = pdf.createLoadingTask(this.$route.params.url)
      },
      getData() {
        let that = this;
        let element = document.getElementById("pdfPreview");
        Transform(element);
        var initScale = 1;
        this.af = new AlloyFinger(element, {
          rotate: function (evt) {  //实现旋转
            element.rotateZ += evt.angle;
          },
          multipointStart: function () {
              initScale = element.scaleX;
          },
          pinch: function (evt) {   //实现缩放
            element.scaleX = element.scaleY = initScale * evt.zoom;
          },
          pressMove: function (evt) {   //实现移动
            element.translateX += evt.deltaX;
            element.translateY += evt.deltaY;
            evt.preventDefault();
          },
        });
      },
      prePage(){
        var p = this.pageNum
        p = p>1?p-1:this.pageTotalNum
        this.pageNum = p
      },
      nextPage(){
        var p = this.pageNum
        p = p<this.pageTotalNum?p+1:1
        this.pageNum = p
      },
      password(updatePassword, reason) {
        updatePassword(prompt('password is "123456"'))
      },
      pageLoaded(e){
        this.curPageNum = e
      },
      pdfError(error){
        console.error(error)
      },
    },
    components:{
      pdf
    },
  };
</script>

<style>
#app {
    font-family: Avenir,Helvetica,Arial,sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    width: 100%;
    margin: 0 auto;
    overflow: hidden;
    min-height: 100vh;
}
.pdf-tab {
    display: -ms-flexbox;
    display: flex;
    -ms-flex-wrap: wrap;
    flex-wrap: wrap;
    padding: 0 .4rem;
    -ms-flex-pack: justify;
    justify-content: space-between;
}
.pdf-tab .btn-def {
    border-radius: .2rem;
    font-size: .98rem;
    height: 1.93333rem;
    width: 6.4rem;
    text-align: center;
    line-height: 1.93333rem;
    background: #409eff;
    color: #fff;
    margin-bottom: 1.26667rem;
}
.pdf-total {
    text-align: center;
    font-size: 1.45333rem;
}
.pdf-process, .pdf-total {
    text-align: center;
    font-size: 1.45333rem;
}
.pdf-num {
    margin-bottom: 1.2rem;
}
</style>