调用图片downloadFile下载成功但是临时路径为空？

在模拟器上是可以实现的。但是在iphoneX上。statusCode：200 .TempFilePath:wxfile://      就没有然后了。

wx.downloadFile({       url: 'https://www.parrotfamily.cn/static/image/2019/鉴定卡.jpg',       success(res) {         that.showToast(JSON.stringify(res),300000);         console.log('res:' + JSON.stringify(res));         if (res.statusCode === 200) {           //缓存图片           const fs = wx.getFileSystemManager()           fs.saveFile({             tempFilePath: res.tempFilePath, // 传入一个临时文件路径             success(res) {               that.showToast('保存成功',JSON.stringify(res), 30000);               that.setData({                 bgImage: res.savedFilePath,                 downImageState:true,               })               wx.setStorageSync('image_cache', res.savedFilePath)             },             fail(res){               that.showToast('保存失败', JSON.stringify(res), 30000);             }           })         }       },       fail(res){         this.showToast('下载图片失败',2000);         that.setData({           downImageState: false,         })       }     });