This protocol shall be implemented by any cache used in MapCache.

RegionDownloaderDelegate provides callbacks for monitoring the progress of a tile region download.

Conform to this protocol to receive notifications about download progress, individual tile results, and lifecycle events. All methods have default empty implementations provided via a protocol extension, making each callback optional — implement only the ones you need.

Usage Example

class MyViewController: UIViewController, RegionDownloaderDelegate {

    func startDownload() {
        let downloader = RegionDownloader(forRegion: region, mapCache: cache)
        downloader.delegate = self
        downloader.start()
    }

    // Update a progress bar on percentage changes.
    func regionDownloader(_ downloader: RegionDownloader, didDownloadPercentage percentage: Double) {
        DispatchQueue.main.async {
            self.progressView.progress = Float(percentage / 100.0)
        }
    }

    // Show final counts when done.
    func regionDownloader(_ downloader: RegionDownloader, didFinishDownload tilesDownloaded: TileNumber) {
        DispatchQueue.main.async {
            self.label.text = "Done: \(tilesDownloaded) tiles"
        }
    }
}