Is there any way to bundle map data with an iOS app?

Question

I've got a client interested in an iOS app, but one of the requirements is an offline map. Unfortunately, both Google and iOS maps require an active internet connection to download data. Once you've opened the app up once, I think you can trigger a cache for an area, but you still require that connection.

Is there any way to bundle the actual map data with the app, or would I need to reinvent the wheel by writing my own map code?

Answer 1

If you app is iOS 7+, you have some flexibility by using MKTileOverlay. It allows you to put your own tile set on top of a normal Apple map.

By creating a MKTileOverlay subclass and overload loadTileAtPath: you could check your bundle for the initial state, then maybe a separate cache for tiles loaded when there was an internet connection, and finally use the URL to load the tile when all else fails.

- (void)loadTileAtPath:(MKTileOverlayPath)path
                result:(void (^)(NSData *data, NSError *error))result
{
    if (!result) {
        return;
    }

    NSString *filePath = ...; // Predetermined filename based off of MKTileOverlayPath
    NSData *initialData = [NSData dataWithContentsOfFile:filePath];  
    NSData *cachedData = [self.cache objectForKey:[self URLForTilePath:path]];
    if (initialData) {
        result(initialData, nil);
    } else if (cachedData) {
        result(cachedData, nil);
    } else {
        NSURLRequest *request = [NSURLRequest requestWithURL:[self URLForTilePath:path]];
        [NSURLConnection sendAsynchronousRequest:request queue:self.operationQueue completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
            result(data, connectionError);
        }];
    }
} 

More info and some examples here

Answer 2

I got this issue before and the only way I found was by using a third party map tiles provider called MapBox. They provide an API for iOS and other platforms as well. You can even customize your own maps by using TileMill. The former even allows you to export the map tiles as an MBTiles file which provides a way of storing millions of tiles in a single SQLite database making it possible to store and transfer web maps in a single file.