You can ignore this warning and move ahead with your code if you are sure that the id you are passing does exist within your applications context, if you are not sure then its better to do a null check before accessing the elements in this view because
View v = inflater.inflate(R.layout.fragment_photo_gallery, container, false);
will return null in case "R.layout.fragment_photo_gallery" is incorrect or invalid renderring v as null .
Thus an attempt like this
mGridView = (GridView)v.findViewById(R.id.gridView);
may result in a null pointer exception