Manage offline regions

A newer version of the Maps SDK is available

This page uses v6.4.1 of the Mapbox Maps SDK. A newer version of the SDK is available. Learn about the latest version, v10.1.0, in the Maps SDK documentation.

For more information about uses and limitations, see our Offline maps guide.

ViewController
import Mapbox
import Foundation
class ViewController: UIViewController, MGLMapViewDelegate {
lazy var mapView: MGLMapView = {
let mapView = MGLMapView(frame: CGRect.zero)
mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
mapView.tintColor = .gray
mapView.delegate = self
mapView.translatesAutoresizingMaskIntoConstraints = false
return mapView
}()
lazy var downloadButton: UIButton = {
let downloadButton = UIButton(frame: CGRect.zero)
downloadButton.backgroundColor = UIColor.systemBlue
downloadButton.setTitleColor(UIColor.white, for: .normal)
downloadButton.setTitle("Download Region", for: .normal)
downloadButton.addTarget(self, action: #selector(startOfflinePackDownload), for: .touchUpInside)
downloadButton.layer.cornerRadius = view.bounds.width / 30
downloadButton.translatesAutoresizingMaskIntoConstraints = false
return downloadButton
}()
lazy var tableView: UITableView = {
let tableView = UITableView(frame: CGRect.zero)
tableView.delegate = self
tableView.dataSource = self
tableView.translatesAutoresizingMaskIntoConstraints = false
return tableView
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(mapView)
view.addSubview(tableView)
mapView.addSubview(downloadButton)
let centerCoordinate = CLLocationCoordinate2D(latitude: 22.27933, longitude: 114.16281)
mapView.setCenter(centerCoordinate, zoomLevel: 13, animated: false)
// Set up constraints for map view, table view, and download button.
installConstraints()
}
func setupOfflinePackHandler() {
NotificationCenter.default.addObserver(self,
selector: #selector(offlinePackProgressDidChange),
name: NSNotification.Name.MGLOfflinePackProgressChanged,
object: nil)
}
func installConstraints() {
NSLayoutConstraint.activate([
mapView.topAnchor.constraint(equalTo: view.topAnchor),
mapView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
mapView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
mapView.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.75),
tableView.topAnchor.constraint(equalTo: mapView.bottomAnchor),
tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
tableView.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.4),
downloadButton.topAnchor.constraint(equalTo: view.topAnchor, constant: 100),
downloadButton.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 5),
downloadButton.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.45),
downloadButton.heightAnchor.constraint(equalTo: downloadButton.widthAnchor, multiplier: 0.2)
])
}
/*
For the purposes of this example, remove any offline packs
that exist before the example is re-loaded.
*/
override func viewWillAppear(_ animated: Bool) {
MGLOfflineStorage.shared.resetDatabase { (error) in
if let error = error {
// Handle the error here if packs can't be removed.
print(error)
} else {
MGLOfflineStorage.shared.reloadPacks()
}
}
}
@objc func startOfflinePackDownload(selector: NSNotification) {
// Setup offline pack notification handlers.
setupOfflinePackHandler()
/**
Create a region that includes the current map camera, to be captured
in an offline map. Note: Because tile count grows exponentially as zoom level
increases, you should be conservative with your `toZoomLevel` setting.
*/
let region = MGLTilePyramidOfflineRegion(styleURL: mapView.styleURL,
bounds: mapView.visibleCoordinateBounds,
fromZoomLevel: mapView.zoomLevel,
toZoomLevel: mapView.zoomLevel + 2)
// Store some data for identification purposes alongside the offline pack.
let userInfo = ["name": "\(region.bounds)"]
let context = NSKeyedArchiver.archivedData(withRootObject: userInfo)
// Create and register an offline pack with the shared offline storage object.
MGLOfflineStorage.shared.addPack(for: region, withContext: context) { (pack, error) in
guard error == nil else {
// Handle the error if the offline pack couldn’t be created.
print("Error: \(error?.localizedDescription ?? "unknown error")")
return
}
// Begin downloading the map for offline use.
pack!.resume()
}
}
// MARK: - MGLOfflinePack notification handlers
@objc func offlinePackProgressDidChange(notification: NSNotification) {
/**
Get the offline pack this notification is referring to,
along with its associated metadata.
*/
if let pack = notification.object as? MGLOfflinePack,
let userInfo = NSKeyedUnarchiver.unarchiveObject(with: pack.context) as? [String: String] {
// At this point, the offline pack has finished downloading.
if pack.state == .complete {
let byteCount = ByteCountFormatter.string(fromByteCount: Int64(pack.progress.countOfBytesCompleted), countStyle: ByteCountFormatter.CountStyle.memory)
let packName = userInfo["name"] ?? "unknown"
print("""
Offline pack “\(packName)” completed download:
- Bytes: \(byteCount)
- Resource count: \(pack.progress.countOfResourcesCompleted)")
""")
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.MGLOfflinePackProgressChanged,
object: nil)
}
}
// Reload the table to update the progress percentage for each offline pack.
self.tableView.reloadData()
}
}
fileprivate extension MGLOfflinePackProgress {
var percentCompleted: Float {
let percentage = Float((countOfResourcesCompleted / countOfResourcesExpected) * 100)
return percentage
}
var formattedCountOfBytesCompleted: String {
return ByteCountFormatter.string(fromByteCount: Int64(countOfBytesCompleted),
countStyle: .memory)
}
}
extension ViewController: UITableViewDelegate, UITableViewDataSource {
// Create the table view which will display the downloaded regions.
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let packs = MGLOfflineStorage.shared.packs {
return packs.count
} else {
return 0
}
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let label = UILabel()
label.backgroundColor = UIColor.systemBlue
label.textColor = UIColor.white
label.font = UIFont.preferredFont(forTextStyle: .headline)
label.textAlignment = .center
if MGLOfflineStorage.shared.packs != nil {
label.text = "Offline maps"
} else {
label.text = "No offline maps"
}
return label
}
func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 50.0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell.init(style: .subtitle, reuseIdentifier: "cell")
if let packs = MGLOfflineStorage.shared.packs {
let pack = packs[indexPath.row]
cell.textLabel?.text = "Region \(indexPath.row + 1): size: \(pack.progress.formattedCountOfBytesCompleted)"
cell.detailTextLabel?.text = "Percent completion: \(pack.progress.percentCompleted)%"
}
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
guard let packs = MGLOfflineStorage.shared.packs else { return }
if let selectedRegion = packs[indexPath.row].region as? MGLTilePyramidOfflineRegion {
mapView.setVisibleCoordinateBounds(selectedRegion.bounds, animated: true)
}
}
}