wx.openDocument打开pdf没有反应 ？

ios系统真机测试时用wx.openDocument打开pdf文件没有反应，打印结果已经进入success回调 但是没打开pdf文件

wx.downloadFile({               url: result.data.data.fileUrl,                     success: function (res) {                 console.log('wx.downloadFile成功，', res)                 if (res.statusCode == 200) {                                        let Path = res.tempFilePath                   console.log('res.statusCode == 200,开始wx.openDocument')                    wx.openDocument({                     filePath: Path,                                     success: function (res) {                       console.log('wx.openDocument success')                       setTimeout(() => {                         _this.canSign = true                       }, 1000);                     },                     fail: function (res) {                       console.log(res, 'wx.openDocument fail')                     }                   })                 }               },               fail: function (res) {                console.log(res)                        }             })