Use OfflineManager and TileStore to download a region
By default, users may download up to 750 tile packs for offline
use across all regions. If the number exceeds the limit, any loadRegion call will fail until excess regions are deleted. This limit is subject
to change. Contact Mapbox if you require a higher limit. Additional charges may apply.
OfflineManagerExample.swift
// swiftlint:disable file_length
import Foundation
import UIKit
import MapboxMaps
/// Example that shows how to use OfflineManager and TileStore to
/// download regions for offline use.
///
/// By default, users may download up to 750 tile packs for offline
/// use across all regions. If the limit is hit, any loadRegion call
/// will fail until excess regions are deleted. This limit is subject
/// to change. Please contact Mapbox if you require a higher limit.
/// Additional charges may apply.
final class OfflineManagerExample: UIViewController, NonMapViewExampleProtocol {
// This example uses a Storyboard to setup the following views
@IBOutlet private var mapViewContainer: UIView!
@IBOutlet private var logView: UITextView!
@IBOutlet private var button: UIButton!
@IBOutlet private var stylePackProgressView: UIProgressView!
@IBOutlet private var tileRegionProgressView: UIProgressView!
@IBOutlet private var progressContainer: UIView!
private var mapView: MapView?
private var tileStore: TileStore?
private var logger: OfflineManagerLogWriter!
private var cancelables = Set<AnyCancelable>()
// Default MapInitOptions. If you use a custom path for a TileStore, you would
// need to create a custom MapInitOptions to reference that TileStore.
private lazy var mapInitOptions: MapInitOptions = {
MapInitOptions(cameraOptions: CameraOptions(center: tokyoCoord, zoom: tokyoZoom),
styleURI: .satelliteStreets)
}()
private lazy var offlineManager: OfflineManager = {
return OfflineManager()
}()
// Regions and style pack downloads
private var downloads: [Cancelable] = []
private let tokyoCoord = CLLocationCoordinate2D(latitude: 35.682027, longitude: 139.769305)
private let tokyoZoom: CGFloat = 12
private let tileRegionId = "myTileRegion"
private enum State {
case unknown
case initial
case downloading
case downloaded
case mapViewDisplayed
case finished
}
deinit {
OfflineSwitch.shared.isMapboxStackConnected = true
removeTileRegionAndStylePack()
}
override func viewDidLoad() {
super.viewDidLoad()
// Initialize a logger that writes into the text view
logger = OfflineManagerLogWriter(textView: logView)
state = .initial
// The following line is just for testing purposes.
finish()
}
// MARK: - Actions
private func downloadTileRegions() {
guard let tileStore = tileStore else {
preconditionFailure()
}
precondition(downloads.isEmpty)
let dispatchGroup = DispatchGroup()
var downloadError = false
// - - - - - - - -
// 1. Create style package with loadStylePack() call.
let stylePackLoadOptions = StylePackLoadOptions(glyphsRasterizationMode: .ideographsRasterizedLocally,
metadata: ["tag": "my-satellite-style-pack"])!
dispatchGroup.enter()
let stylePackDownload = offlineManager.loadStylePack(for: .satelliteStreets, loadOptions: stylePackLoadOptions) { [weak self] progress in
// These closures do not get called from the main thread. In this case
// we're updating the UI, so it's important to dispatch to the main
// queue.
DispatchQueue.main.async {
guard let stylePackProgressView = self?.stylePackProgressView else {
return
}
self?.logger?.log(message: "StylePack = \(progress)", category: "Example")
stylePackProgressView.progress = Float(progress.completedResourceCount) / Float(progress.requiredResourceCount)
}
} completion: { [weak self] result in
DispatchQueue.main.async {
defer {
dispatchGroup.leave()
}
switch result {
case let .success(stylePack):
self?.logger?.log(message: "StylePack = \(stylePack)", category: "Example")
case let .failure(error):
self?.logger?.log(message: "stylePack download Error = \(error)", category: "Example", color: .red)
downloadError = true
}
}
}
// - - - - - - - -
// 2. Create an offline region with tiles for the satellite streets style.
// If you are using a raster tileset you may need to set a different pixelRatio. The default is UIScreen.main.scale.
let satelliteOptions = TilesetDescriptorOptions(styleURI: .satelliteStreets,
zoomRange: 0...16,
tilesets: nil)
let satelliteDescriptor = offlineManager.createTilesetDescriptor(for: satelliteOptions)
// Load the tile region
let tileRegionLoadOptions = TileRegionLoadOptions(
geometry: .point(Point(tokyoCoord)),
descriptors: [satelliteDescriptor],
metadata: ["tag": "my-satellite-tile-region"],
acceptExpired: true)!
// Use the the default TileStore to load this region. You can create
// custom TileStores are are unique for a particular file path, i.e.
// there is only ever one TileStore per unique path.
dispatchGroup.enter()
let tileRegionDownload = tileStore.loadTileRegion(forId: tileRegionId,
loadOptions: tileRegionLoadOptions) { [weak self] (progress) in
// These closures do not get called from the main thread. In this case
// we're updating the UI, so it's important to dispatch to the main
// queue.
DispatchQueue.main.async {
guard let tileRegionProgressView = self?.tileRegionProgressView else {
return
}
self?.logger?.log(message: "\(progress)", category: "Example")
// Update the progress bar
tileRegionProgressView.progress = Float(progress.completedResourceCount) / Float(progress.requiredResourceCount)
}
} completion: { [weak self] result in
DispatchQueue.main.async {
defer {
dispatchGroup.leave()
}
switch result {
case let .success(tileRegion):
self?.logger?.log(message: "tileRegion = \(tileRegion)", category: "Example")
case let .failure(error):
self?.logger?.log(message: "tileRegion download Error = \(error)", category: "Example", color: .red)
downloadError = true
}
}
}
// Wait for both downloads before moving to the next state
dispatchGroup.notify(queue: .main) {
self.downloads = []
self.state = downloadError ? .finished : .downloaded
}
downloads = [stylePackDownload, tileRegionDownload]
state = .downloading
}
private func cancelDownloads() {
// Canceling will trigger `.canceled` errors that will then change state
downloads.forEach { $0.cancel() }
}
private func logDownloadResult<T, Error>(message: String, result: Result<[T], Error>) {
switch result {
case let .success(array):
logger?.log(message: message, category: "Example")
for element in array {
logger?.log(message: "\t\(element)", category: "Example")
}
case let .failure(error):
logger?.log(message: "\(message) \(error)", category: "Example", color: .red)
}
}
private func showDownloadedRegions() {
guard let tileStore = tileStore else {
preconditionFailure()
}
offlineManager.allStylePacks { result in
self.logDownloadResult(message: "Style packs:", result: result)
}
tileStore.allTileRegions { result in
self.logDownloadResult(message: "Tile regions:", result: result)
}
logger?.log(message: "\n", category: "Example")
}
// Remove downloaded region and style pack
private func removeTileRegionAndStylePack() {
// Clean up after the example. Typically, you'll have custom business
// logic to decide when to evict tile regions and style packs
// Remove the tile region with the tile region ID.
// Note this will not remove the downloaded tile packs, instead, it will
// just mark the tileset as not a part of a tile region. The tiles still
// exists in a predictive cache in the TileStore.
tileStore?.removeTileRegion(forId: tileRegionId)
// Set the disk quota to zero, so that tile regions are fully evicted
// when removed.
// This removes the tiles from the predictive cache.
tileStore?.setOptionForKey(TileStoreOptions.diskQuota, value: 0)
// Remove the style pack with the style uri.
// Note this will not remove the downloaded style pack, instead, it will
// just mark the resources as not a part of the existing style pack. The
// resources still exists in the disk cache.
offlineManager.removeStylePack(for: .satelliteStreets)
}
// MARK: - State changes
@IBAction private func didTapButton(_ button: UIButton) {
switch state {
case .unknown:
state = .initial
case .initial:
downloadTileRegions()
case .downloading:
// Cancel
cancelDownloads()
case .downloaded:
state = .mapViewDisplayed
case .mapViewDisplayed:
showDownloadedRegions()
state = .finished
case .finished:
removeTileRegionAndStylePack()
showDownloadedRegions()
state = .initial
}
}
private var state: State = .unknown {
didSet {
logger?.log(message: "Changing state from \(oldValue) -> \(state)", category: "Example", color: .orange)
switch (oldValue, state) {
case (_, .initial):
resetUI()
self.tileStore = TileStore.default
logger?.log(message: "Enabling HTTP stack network connection", category: "Example", color: .orange)
OfflineSwitch.shared.isMapboxStackConnected = true
case (.initial, .downloading):
// Can cancel
button.setTitle("Cancel Downloads", for: .normal)
case (.downloading, .downloaded):
logger?.log(message: "Disabling HTTP stack network connection", category: "Example", color: .orange)
OfflineSwitch.shared.isMapboxStackConnected = false
enableShowMapView()
case (.downloaded, .mapViewDisplayed):
showMapView()
case (.mapViewDisplayed, .finished),
(.downloading, .finished):
button.setTitle("Reset", for: .normal)
default:
fatalError("Invalid transition from \(oldValue) to \(state)")
}
}
}
// MARK: - UI changes
private func resetUI() {
logger?.reset()
logView.textContainerInset.bottom = view.safeAreaInsets.bottom
logView.scrollIndicatorInsets.bottom = view.safeAreaInsets.bottom
progressContainer.isHidden = false
stylePackProgressView.progress = 0.0
tileRegionProgressView.progress = 0.0
button.setTitle("Start Downloads", for: .normal)
mapView?.removeFromSuperview()
mapView = nil
}
private func enableShowMapView() {
button.setTitle("Show Map", for: .normal)
}
private func showMapView() {
button.setTitle("Show Downloads", for: .normal)
progressContainer.isHidden = true
let mapView = MapView(frame: mapViewContainer.bounds, mapInitOptions: mapInitOptions)
mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
mapViewContainer.addSubview(mapView)
// Add a point annotation that shows the point geometry that were passed
// to the tile region API.
mapView.mapboxMap.onStyleLoaded.observeNext { [weak self] _ in
guard let self = self,
let mapView = self.mapView else {
return
}
var pointAnnotation = PointAnnotation(coordinate: self.tokyoCoord)
pointAnnotation.image = .init(image: UIImage(named: "dest-pin")!, name: "custom-marker")
pointAnnotation.iconOffset = [0, 12]
let pointAnnotationManager = mapView.annotations.makePointAnnotationManager()
pointAnnotationManager.annotations = [pointAnnotation]
}.store(in: &cancelables)
self.mapView = mapView
}
}
// MARK: - Convenience classes for tile and style classes
extension TileRegionLoadProgress {
public override var description: String {
"TileRegionLoadProgress: \(completedResourceCount) / \(requiredResourceCount)"
}
}
extension StylePackLoadProgress {
public override var description: String {
"StylePackLoadProgress: \(completedResourceCount) / \(requiredResourceCount)"
}
}
extension TileRegion {
public override var description: String {
"TileRegion \(id): \(completedResourceCount) / \(requiredResourceCount)"
}
}
extension StylePack {
public override var description: String {
"StylePack \(styleURI): \(completedResourceCount) / \(requiredResourceCount)"
}
}
/// Convenience logger to write logs to the text view
final class OfflineManagerLogWriter {
weak var textView: UITextView?
var log: NSMutableAttributedString
init(textView: UITextView) {
self.log = NSMutableAttributedString()
self.textView = textView
}
func reset() {
log = NSMutableAttributedString()
textView?.attributedText = log
}
func log(message: String, category: String?, color: UIColor = .black) {
print("[\(category ?? "")] \(message)")
DispatchQueue.main.async { [weak self] in
guard let textView = self?.textView,
let log = self?.log else {
return
}
let message = NSMutableAttributedString(string: "\(message)\n", attributes: [NSAttributedString.Key.foregroundColor: color])
log.append(message)
textView.attributedText = log
}
}
}
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