Promise.all函数的使用

 Promise.all([this.getCity('guess'),this.getCity('hot'),this.getCity('group')]).then(res=>{
    // console.log(res[1].data)
    this.setData({
      guessCity:res[0].data,
      hotCity:res[1].data,
      cities:this.formateCities (res[2].data)
    })
  })