@Override
        public ITileLayer createTileLayer(final TileCache tileCache, final MapViewPosition mapViewPosition) {
            final InputStream mapStream = createMapFileInputStream(this.mapUri);
            if (mapStream == null) {
                return null;
            }
            final MapFile mf = createMapFile(String.valueOf(this.mapUri), mapStream);
            if (mf != null) {
                MapProviderFactory.setLanguages(mf.getMapLanguages());
                return new RendererLayer(tileCache, mf, mapViewPosition, false, true, false, AndroidGraphicFactory.INSTANCE);
            }
            MapsforgeMapProvider.getInstance().invalidateMapUri(mapUri);
            return null;
        }
Create new render layer, if mapfile exists
main/src/main/java/cgeo/geocaching/maps/mapsforge/MapsforgeMapProvider.java