<!-- index.ttml -->
<view class="container">
  <button type="primary" bindtap="saveFile">保存临时文件到本地永久目录</button>
</view>

// index.js
const url =
  "https://sf1-cdn-tos.douyinstatic.com/obj/microapp/frontend/download.png"
Page({
  data: {
    // tempFilePath: ""
  },
  saveFile() {
    tt.downloadFile({
      url,
      success: (res) => {
        console.log("临时文件下载成功,下载路径: " + res.tempFilePath)
        tt.saveFile({
          // 参数: 需传入文件临时路径tempFilePath
          tempFilePath: res.tempFilePath,
          success: (data) => {
            // 返回参数中的savedFilePath属性为保存的本地文件路径
            console.log("保存成功, 本地路径为: ", data.savedFilePath)
            tt.showModal({
              content: "临时文件保存成功",
              showCancel: false,
            })
          },
          fail: (res) => {
            // 当 API 执行失败后调用, 预定义返回消息格式为${API_NAME}:fail
            console.log("临时文件保存失败", res.errMsg)
            tt.showModal({
              content: "临时文件保存失败",
              showCancel: false,
            })
          },
          complete: (res) => {
            // 当 API 执行完成（无论成功或者失败）后都会调用, 预定义返回消息格式为${API_NAME}:ok / fail
            console.log("接口已调用", res.errMsg)
          },
        })
      },
      fail: (res) => {
        console.log("下载失败: ", res.errMsg)
      },
    })
  },
})