Offline Maps

An object conforming to the MGLOfflineRegion protocol determines which resources are required by an MGLOfflinePack object.

MGLOfflineStorage implements a singleton (shared object) that manages offline packs. All of this class’s instance methods are asynchronous, reflecting the fact that offline resources are stored in a database. The shared object maintains a canonical collection of offline packs in its packs property.

Related examples

See the Download an offline map example to learn how to create and register an offline pack for a defined region.

An MGLOfflinePack represents a collection of resources necessary for viewing a region offline to a local database.

To create an instance of MGLOfflinePack, use the +[MGLOfflineStorage addPackForRegion:withContext:completionHandler:] method. A pack created using -[MGLOfflinePack init] is immediately invalid.

Example

MGLOfflineStorage.shared.addPack(for: region, withContext: context) { (pack, error) in
    guard let pack = pack else {
        // If adding the pack fails, log an error to console.
        print("Error:", error?.localizedDescription ?? "unknown error adding pack at \(#file)(\(#line)) in \(#function)")
        return
    }

    // Start an MGLOfflinePack download
    pack.resume()
}

A structure containing information about an offline pack’s current download progress.

The state an offline pack is currently in.

An offline region defined by a style URL, geographic coordinate bounds, and range of zoom levels.

To minimize the resources required by an irregularly shaped offline region, use the MGLShapeOfflineRegion class instead.

Example

let northeast = CLLocationCoordinate2D(latitude: 40.989329, longitude: -102.062592)
let southwest = CLLocationCoordinate2D(latitude: 36.986207, longitude: -109.049896)
let bbox = MGLCoordinateBounds(sw: southwest, ne: northeast)

let region = MGLTilePyramidOfflineRegion(styleURL: MGLStyle.lightStyleURL, bounds: bbox, fromZoomLevel: 11, toZoomLevel: 14)
let context = "Tile Pyramid Region".data(using: .utf8)
MGLOfflineStorage.shared.addPack(for: region, withContext: context!)

Related examples

See the Download an offline map example to learn how to define an offline region to be downloaded to a user’s device.

An offline region defined by a style URL, geographic shape, and range of zoom levels.

Example

var coordinates = [
    CLLocationCoordinate2D(latitude: 45.522585, longitude: -122.685699),
    CLLocationCoordinate2D(latitude: 45.534611, longitude: -122.708873),
    CLLocationCoordinate2D(latitude: 45.530883, longitude: -122.678833)
]

let triangle = MGLPolygon(coordinates: &coordinates, count: UInt(coordinates.count))
let region = MGLShapeOfflineRegion(styleURL: MGLStyle.lightStyleURL, shape: triangle, fromZoomLevel: 11, toZoomLevel: 14)
let context = "Triangle Region".data(using: .utf8)
MGLOfflineStorage.shared.addPack(for: region, withContext: context!)

This class requires fewer resources than MGLTilePyramidOfflineRegion for irregularly shaped regions.