Taking a web map offline allows users continued productivity when their network connectivity is poor or nonexistent. For example, by taking a map offline, a field worker inspecting utility lines in remote areas could still access a feature's location and attribute information.
How to use the sample
When the map loads, zoom to the extent you want to take offline. The red border shows the extent that will be downloaded. Tap the "Generate offline map" button to start the offline map job. The progress view will show the job's progress. When complete, the offline map will replace the online map in the map view.
How it works
Create an AGSMap with an AGSPortalItem pointing to the web map.
Create AGSGenerateOfflineMapParameters with AGSOfflineMapTask.defaultGenerateOfflineMapParameters(withAreaOfInterest:completion:) specifying the download area geometry.
Create an AGSOfflineMapTask with the map.
Create the AGSGenerateOfflineMapJob with AGSOfflineMapTask.generateOfflineMapJob(with:downloadDirectory:) and start it with AGSGenerateOfflineMapJob.start(statusHandler:completion:).
When the job is done, get the offline map within the completion closure.
Relevant API
AGSGenerateOfflineMapJob
AGSGenerateOfflineMapParameters
AGSGenerateOfflineMapResult
AGSOfflineMapTask
AGSPortal
AGSPortalItem
About the data
The map used in this sample shows the Naperville water network within Naperville, IL, USA, with cartography designed for web and mobile devices with offline support.
Additional information
The creation of the offline map can be fine-tuned using "Generate offline map (overrides)" sample, or by using "Generate offline map with local basemap" sample to achieve more customized results.
Tags
download, offline, save, web map
Sample Code
GenerateOfflineMapViewController.swift
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//// Copyright 2018 Esri.//// Licensed under the Apache License, Version 2.0 (the "License");// you may not use this file except in compliance with the License.// You may obtain a copy of the License at//// http://www.apache.org/licenses/LICENSE-2.0//// Unless required by applicable law or agreed to in writing, software// distributed under the License is distributed on an "AS IS" BASIS,// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.// See the License for the specific language governing permissions and// limitations under the License.//import UIKit
import ArcGIS
classGenerateOfflineMapViewController: UIViewController{
@IBOutletvar mapView: AGSMapView!
@IBOutletvar extentView: UIView!
@IBOutletvar barButtonItem: UIBarButtonItem!
@IBOutletvar progressView: UIProgressView!
@IBOutletvar progressLabel: UILabel!
@IBOutletvar progressParentView: UIView!
@IBOutletvar cancelButton: UIButton!
privatevar portalItem: AGSPortalItem?
privatevar parameters: AGSGenerateOfflineMapParameters?
privatevar offlineMapTask: AGSOfflineMapTask?
privatevar generateOfflineMapJob: AGSGenerateOfflineMapJob?
privatevar jobProgressObservation: NSKeyValueObservation?
overridefuncviewDidLoad() {
super.viewDidLoad()
// add the source code button item to the right of navigation bar (navigationItem.rightBarButtonItem as!SourceCodeBarButtonItem).filenames = ["GenerateOfflineMapViewController"]
addMap()
}
privatefuncaddMap() {
// portal for the web maplet portal =AGSPortal.arcGISOnline(withLoginRequired: false)
// portal item for web maplet portalItem =AGSPortalItem(portal: portal, itemID: "acc027394bc84c2fb04d1ed317aac674")
self.portalItem = portalItem
// map from portal itemlet map =AGSMap(item: portalItem)
// assign map to the map view mapView.map = map
// disable the bar button item until the map loads mapView.map?.load { [weakself] (error) inguardletself=selfelse {
return }
iflet error = error {
if (error asNSError).code !=NSUserCancelledError {
// show errorself.presentAlert(error: error)
}
return }
self.barButtonItem.isEnabled =true }
// instantiate offline map task offlineMapTask =AGSOfflineMapTask(portalItem: portalItem)
// setup extent view extentView.layer.borderColor =UIColor.red.cgColor
extentView.layer.borderWidth =3 }
privatefunctakeMapOffline() {
guardlet offlineMapTask = offlineMapTask,
let parameters = parameters else {
return }
let downloadDirectory = getNewOfflineMapDirectoryURL()
let generateOfflineMapJob = offlineMapTask.generateOfflineMapJob(with: parameters, downloadDirectory: downloadDirectory)
self.generateOfflineMapJob = generateOfflineMapJob
// observe the job's progress jobProgressObservation = generateOfflineMapJob.progress.observe(\.fractionCompleted, options: .new) { [weakself] (progress, _) inDispatchQueue.main.async {
// update progress labelself?.progressLabel.text = progress.localizedDescription
// update progress viewself?.progressView.progress =Float(progress.fractionCompleted)
}
}
// unhide the progress parent view progressParentView.isHidden =false// start the job generateOfflineMapJob.start(statusHandler: nil) { [weakself] (result, error) inguardletself=selfelse {
return }
// remove KVO observerself.jobProgressObservation =niliflet error = error {
// do not display error if user simply cancelled the requestif (error asNSError).code !=NSUserCancelledError {
self.presentAlert(error: error)
}
} elseiflet result = result {
self.offlineMapGenerationDidSucceed(with: result)
}
}
}
/// Called when the generate offline map job finishes successfully.////// - Parameter result: The result of the generate offline map job.funcofflineMapGenerationDidSucceed(withresult: AGSGenerateOfflineMapResult) {
// Show any layer or table errors to the user.iflet layerErrors = result.layerErrors as? [AGSLayer: Error],
let tableErrors = result.tableErrors as? [AGSFeatureTable: Error],
!(layerErrors.isEmpty && tableErrors.isEmpty) {
let errorMessages = layerErrors.map { "\($0.key.name): \($0.value.localizedDescription)" } + tableErrors.map { "\($0.key.displayName): \($0.value.localizedDescription)" }
presentAlert(title: "Offline Map Generated with Errors",
message: "The following error(s) occurred while generating the offline map:\n\n\(errorMessages.joined(separator: "\n"))")
}
// disable cancel button cancelButton.isEnabled =false// assign offline map to map view mapView.map = result.offlineMap
}
// MARK: - Actions@IBActionfuncgenerateOfflineMapAction() {
// disable bar button item barButtonItem.isEnabled =false// hide the extent view extentView.isHidden =true// show progress hudUIApplication.shared.showProgressHUD(message: "Getting default parameters")
// get the area outlined by the extent viewlet areaOfInterest = extentViewFrameToEnvelope()
// default parameters for offline map task offlineMapTask?.defaultGenerateOfflineMapParameters(withAreaOfInterest: areaOfInterest) { [weakself] (parameters: AGSGenerateOfflineMapParameters?, error: Error?) in// dismiss progress hudUIApplication.shared.hideProgressHUD()
guardletself=selfelse { return }
iflet parameters = parameters {
// The parameters for creating a job of offline maps generation.self.parameters = parameters
// Take map offline.self.takeMapOffline()
} elseiflet error = error {
self.presentAlert(error: error)
}
}
}
@IBActionfunccancelAction() {
// cancel generate offline map job generateOfflineMapJob?.progress.cancel()
progressParentView.isHidden =true progressView.progress =0 progressLabel.text =""// enable take map offline bar button item barButtonItem.isEnabled =true// unhide the extent view extentView.isHidden =false }
// MARK: - Helper methodsprivatefuncshowLoginQueryAlert() {
let alertController =UIAlertController(title: nil, message: "This sample requires you to login in order to take the map's basemap offline. Would you like to continue?", preferredStyle: .alert)
let loginAction =UIAlertAction(title: "Login", style: .default) { [weakself] (_) inself?.addMap()
}
let cancelAction =UIAlertAction(title: "Cancel", style: .cancel)
alertController.addAction(cancelAction)
alertController.addAction(loginAction)
alertController.preferredAction = loginAction
present(alertController, animated: true)
}
privatefuncextentViewFrameToEnvelope() -> AGSEnvelope {
let frame = mapView.convert(extentView.frame, from: view)
// the lower-left cornerlet minPoint = mapView.screen(toLocation: frame.origin)
// the upper-right cornerlet maxPoint = mapView.screen(toLocation: CGPoint(x: frame.maxX, y: frame.maxY))
// return the envenlope covering the entire extent framereturnAGSEnvelope(min: minPoint, max: maxPoint)
}
privatefuncgetNewOfflineMapDirectoryURL() -> URL {
// get a suitable directory to place fileslet documentDirectoryURL =FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!// create a unique name based on current timestamplet formattedDate =ISO8601DateFormatter().string(from: Date())
return documentDirectoryURL.appendingPathComponent("\(formattedDate)")
}
}