mapbox save as image

gistfile1.m

- (UIImage *) loadMapImage {
    const int MINZOOM = 13;
    const int MAXZOOM = 17;
    
    // TODO: calculate these from list of cycle hire locations
    const float MINLAT = 51.483145;  //minimum and max lattitude in degrees
    const float MAXLAT = 51.542138;
    const float MINLONG = -0.2242237;  //min and max longitutde in degrees
    const float MAXLONG = -0.002275;
    
    for (int zoom = MINZOOM; zoom <= MAXZOOM; zoom++){
        NSLog(@"Downloading zoom level %d", zoom);
        int n = pow(2.0, zoom);   //n=2^ZOOM
        int xMin = floor(((MINLONG + 180.0) / 360.0) * n);  //longitude in degrees
        int yMax = floor((1.0 - (logf(tanf(MINLAT * M_PI / 180.0) + 1.0 / cosf(MINLAT * M_PI / 180.0)) / M_PI)) / 2.0 * n);  //latitude in degrees
        int xMax = floor(((MAXLONG + 180.0) / 360.0) * n);  //longitude in degrees
        int yMin = floor((1.0 - (logf(tanf(MAXLAT * M_PI / 180.0) + 1.0 / cosf(MAXLAT * M_PI / 180.0)) / M_PI)) / 2.0 * n);
        NSLog(@"n=%d, xMin=%d, xMax=%d, yMin=%d, yMax=%d",n,xMin,xMax,yMin,yMax);
        int totalTiles = (xMax + 1 - xMin) * (yMax + 1 - yMin);
        NSLog(@"Total tiles for this zoom level: %d", totalTiles);
        for (int x = xMin; x<=xMax; x++){
            // TODO: Create & drain autorelease pool for each iteration of the outer loop (we don't use the returned UIImages)
            for (int y = yMin; y <= yMax; y++){
                int currentTiles = (x - xMin) * (yMax + 1 - yMin) + (y - yMin + 1);
                NSLog(@"Downloading zoom=%d,x=%d,y=%d (%d/%d)", zoom, x, y, currentTiles, totalTiles);
                NSLog(@"progress = %f0.1", ((float) currentTiles) / totalTiles);
                UIImage *tileImage = [_switchController.mapView.tileSource imageForTile:RMTileMake(x, y, zoom) inCache:[_switchController.mapView tileCache]];
                return tileImage;
                break;
            }
        }
    }
}