//保存视频

  handleDownload() {
    wx.showLoading({
      title: '下载中',
      mask:true
    })
    let fileName = new Date().valueOf();
    wx.downloadFile({
      url: "http://wxsnsdy.tc.qq.com/105/20210/snsdyvideodownload?filekey=30280201010421301f0201690402534804102ca905ce620b1241b726bc41dcff44e00204012882540400&bizid=1023&hy=SH&fileparam=302c020101042530230204136ffd93020457e3c4ff02024ef202031e8d7f02030f42400204045a320a0201000400",
      filePath: wx.env.USER_DATA_PATH + '/' + fileName + '.mp4',
      success: res => {
        console.log(res)
        wx.hideLoading()
        let filePath = res.filePath; //下载到本地获取临时路径
        let fileMgr = wx.getFileSystemManager();
        wx.saveVideoToPhotosAlbum({ //保存到相册
          filePath,
          success: file => {
            console.log(file)
            wx.showToast({
              title: '视频保存成功',
              duration:3000,
              icon:'none'
            })
            fileMgr.unlink({ //删除临时文件
              filePath: wx.env.USER_DATA_PATH + '/' + fileName + '.mp4',
            })
          },
          fail: err => {
            console.log(err)
            fileMgr.unlink({ //删除临时文件
              filePath: wx.env.USER_DATA_PATH + '/' + fileName + '.mp4',
            })
            wx.showToast({
              title: '视频保存失败',
              duration:3000,
              icon:'none'
            })
          },
          complete() {
            wx.hideLoading()
          }
        })
      },
      fail(e) {
        wx.showToast({
          title: '视频保存失败',
          duration:3000,
          icon:'none'
        })
      },
      complete() {
        // wx.hideLoading();
      }
    })
  },
  //获取用户授权
  onStartDownload() {
    wx.getSetting({
      success:(res)=> {


        if (res.authSetting['scope.writePhotosAlbum'] === undefined) {
          wx.authorize({
            scope: 'scope.writePhotosAlbum',
            success:()=> {
              console.log('打开了授权')
              this.handleDownload()
            },
            fail:(err)=> {
              
            }
          })
        } else if (!res.authSetting['scope.writePhotosAlbum']) {
          wx.openSetting({
            success:(res)=> {
              console.log(res)
              if (res.authSetting['scope.writePhotosAlbum']) {
                console.log('授权了')
                this.handleDownload()
              } else {
              
              }
            },
            fail:(err)=> {
             
            },
          })
        } else {
          this.handleDownload()
        }
      }
    })
  },

报错内容：errMsg: "saveVideoToPhotosAlbum:fail ENOENT: no such file。

ios 与安卓系统真机调试没有问题，但是真机预览保存失败。