返回上一页的截停处理

WillPopScope(
  onWillPop: () async{
    if(isSubmit || (state.value['schemes']??[]).length < 1) {
      return true;
    }else {
      showDialog(context, '您还未提交，确认退出？', cancelTitle: '取消', comfrimTitle: '确认', comfirm: () {
        Navigator.pop(context);
      });
      return false;
    }
  },
  child: ...
)