Find places

Learn how to search for places of interest, such as hotels, cafes, and gas stations using the geocoding service.

find places

Geocoding is the process of transforming an address or place name to a location on the earth's surface. A geocoding service allows you to quickly find places that meet specific criteria.

In this tutorial, you use a picklist in the user interface to select a category of places, for example, coffee shops or gas stations. You locate all the places that match this category by accessing a geocoding service. The places are displayed on the map so that you can click on them to get further information.

Prerequisites

The following are required for this tutorial:

  1. An ArcGIS account to access your API keys. If you don't have an account, sign up for free.
  2. Your system meets the system requirements.

Steps

Open the Xcode project

  1. To start the tutorial, complete the Display a map tutorial or download and unzip the solution.

  2. Open the .xcodeproj file in Xcode.

  3. If you downloaded the solution project, set your API key.

    An API Key enables access to services, web maps, and web scenes hosted in ArcGIS Online.

    1. Go to your developer dashboard to get your API key. For these tutorials, use your default API key. It is scoped to include all of the services demonstrated in the tutorials.

    2. In Xcode, in the Project Navigator, click AppDelegate.swift.

    3. In the editor, set the APIKey property on the AGSArcGISRuntimeEnvironment with your API key.


      AppDelegate.swift
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          func application(_ application: UIApplication,
                           didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
              // Note: it is not best practice to store API keys in source code.
              // The API key is referenced here for the convenience of this tutorial.
      
              AGSArcGISRuntimeEnvironment.apiKey = "YOUR_API_KEY"
      
              return true
          }
      
      Expand

Add a category picker

You will add a Picker View to the user interface to show categories of places to find, for example, coffee shops or gas stations. Each category will be displayed with a different color on the map.

  1. Open main.storyboard and select the Map View. In the Object library select a Picker View and drag it over the View containing the Map View such that it becomes a child of the View.

    • Adjust the height of the Picker View to approximately 70 pixels and anchor it to the bottom of the View.

    • Adjust the height of the Map View anchor to the top of the Picker View.

    • Set the data source outlet to the view controller.

    • Set the delegate outlet to the view controller.

    • Control-drag the Picker View to the view controller to define a new referencing outlet. Name the outlet categoryPicker.

    UIPickerView is a standard UIKit component. Learn more at developer.apple.com.

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        @IBOutlet weak var categoryPicker: UIPickerView!
    
  2. In the ViewController.swift file, update the class declaration to add the Picker View delegate and data source protocols. Also add the touch delegate protocol (AGSGeoViewTouchDelegate) for the map view:

    The AGSGeoViewTouchDelegate is a protocol you adopt to be notified about touch events on the map view. You will use this to identify places on the map and display their attributes.

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    class ViewController: UIViewController,
                            UIPickerViewDelegate,
                            UIPickerViewDataSource,
                            AGSGeoViewTouchDelegate {
    
  3. Add an array of the place categories to search for. Use this to populate a Picker View to allow the user to select a category. Each category is identified with a different color graphic on the map. Declare an array named categories and initialize it with the available categories and colors.

    This tutorial uses category filtering to provide accurate search results based on pre-determined place categories. Feel free to modify this list to your specific requirements.

    This technique uses typealias to define the structure of each element of the array.

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        private typealias Category = (title: String, color: UIColor)
        private let categories: [Category] = [("Coffee shop", .brown),
                                              ("Gas station", .orange),
                                              ("Food", .cyan),
                                              ("Hotel", .blue),
                                              ("Neighborhood", .black),
                                              ("Parks and Outdoors", .green)]
    

Set up the LocatorTask

A locator task is used to search for places using a geocoding service. Results from this search contain the place location and additional information (attributes). Create the locator task along with any variables and methods needed to perform the search and display the results.

  1. Add the following variables to support the search operation.

    • locatorTask is used each time a new search is requested
    • cancelableGeocodeTask is a means to cancel a search that is in progress
    • graphicsOverlay displays the search results on the map
    • isNavigatingObserver is a key-value observer protocol to monitor map navigation. When navigation stops, a new search is performed using the updated visible area of the map.
    • AttributeKeys defines which attributes in the search results you are interested in

    See AGSLocatorTask for more information.

    Use a AGSGraphicsOverlay to display temporary, non-persistent information on a map in its own layer. Visit the Add a point, line, and polygon tutorial to learn more about graphics and graphics overlays.

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        private let locatorTask = AGSLocatorTask(url: URL(string: "https://geocode.arcgis.com/arcgis/rest/services/World/GeocodeServer")!)
        private var cancelableGeocodeTask: AGSCancelable?
    
        private let graphicsOverlay = AGSGraphicsOverlay()
        private var isNavigatingObserver: NSKeyValueObservation?
    
        private struct AttributeKeys {
            static let placeAddress = "Place_addr"
            static let placeName = "PlaceName"
        }
    
  2. Create a method called findPlaces to perform the geocode search operation. The method takes a single parameter to indicate which category of places to search for. This uses the Category type alias you created in a previous step. Verify the map has a valid visible area, otherwise a search should not be attempted.

    The map must be loaded and layers rendered in the view in order for the visibleArea property to be valid.

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        private func findPlaces(forCategory category: Category) {
    
            guard let visibleArea = mapView.visibleArea else { return }
    
        }
    
  3. Add code to clear the results from a prior search and cancel a search if it is still in progress.

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        private func findPlaces(forCategory category: Category) {
    
            guard let visibleArea = mapView.visibleArea else { return }
    
            // Clean up anything from the prior search.
            mapView.callout.dismiss()
            graphicsOverlay.graphics.removeAllObjects()
            cancelableGeocodeTask?.cancel()
    
        }
    
  4. Configure the geocode parameters. Add an AGSGeocodeParameters object to the findPlaces method. Populate it with the search location, the number of results to return, and the result attributes you want to show.

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        private func findPlaces(forCategory category: Category) {
    
            guard let visibleArea = mapView.visibleArea else { return }
    
            // Clean up anything from the prior search.
            mapView.callout.dismiss()
            graphicsOverlay.graphics.removeAllObjects()
            cancelableGeocodeTask?.cancel()
    
            // Configure parameters for the search task.
            let geocodeParameters = AGSGeocodeParameters()
            geocodeParameters.preferredSearchLocation = visibleArea.extent.center
            geocodeParameters.maxResults = 25
            geocodeParameters.resultAttributeNames.append(contentsOf: [AttributeKeys.placeAddress, AttributeKeys.placeName])
    
        }
    
  5. Call the geocode method on the locatorTask using the category title and the geocode parameters. When the asynchronous geocode operation completes, verify that it completed successfully and that results were returned. Iterate over the results and display each location as a graphic with a simple marker symbol. Assign the result's attributes to the graphic.

    Populate the graphicsOverlay with simple marker symbols representing each place returned in the search results. This is very similar to the Add a point, line, and polygon tutorial.

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        private func findPlaces(forCategory category: Category) {
    
            guard let visibleArea = mapView.visibleArea else { return }
    
            // Clean up anything from the prior search.
            mapView.callout.dismiss()
            graphicsOverlay.graphics.removeAllObjects()
            cancelableGeocodeTask?.cancel()
    
            // Configure parameters for the search task.
            let geocodeParameters = AGSGeocodeParameters()
            geocodeParameters.preferredSearchLocation = visibleArea.extent.center
            geocodeParameters.maxResults = 25
            geocodeParameters.resultAttributeNames.append(contentsOf: [AttributeKeys.placeAddress, AttributeKeys.placeName])
    
            cancelableGeocodeTask = locatorTask.geocode(withSearchText: category.title, parameters: geocodeParameters) { [weak self] (results: [AGSGeocodeResult]?, error: Error?) -> Void in
    
                guard let self = self else { return }
                guard error == nil else {
                    print("geocode error", error!.localizedDescription)
                    return
                }
                guard let results = results, results.count > 0 else {
                    print("No places found for category", category.title)
                    return
                }
    
                // Represent each located place as a dot on the map. Each graphic symbol also gets the place attributes so we can
                // show them later when the user taps the graphic.
                for result in results {
                    let placeSymbol = AGSSimpleMarkerSymbol(style: .circle, color: category.color, size: 10.0)
                    placeSymbol.outline = AGSSimpleLineSymbol(style: .solid, color: .white, width: 2)
                    let graphic = AGSGraphic(geometry: result.displayLocation, symbol: placeSymbol, attributes: result.attributes as [String : AnyObject]?)
                    self.graphicsOverlay.graphics.add(graphic)
                }
            }
    
        }
    
  6. Create a method to read the Picker View's selected category and call the findPlaces method.

    It is good coding practice to encapsulate different operations into small and separate methods. This way the concern with getting the user's category selection is separate from searching for a particular category. This practice gives your code flexibility.

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        // Get the current selection in the picker and find places for that category.
        private func findPlacesForCategoryPickerSelection() {
            let categoryIndex = categoryPicker.selectedRow(inComponent: 0)
            guard categoryIndex < categories.count else { return }
            let category = categories[categoryIndex]
            findPlaces(forCategory: category)
        }
    

Add the data source and delegate protocol methods

Delegate interface methods are used to map a request for a specific row in the Picker View to an element in the categories array. When the user selects a row, a search will be performed using the matching category.

  1. Add the UIPickerView data source interface methods to map requests to the categories array:

    Add these new methods at the bottom of ViewController, before the closing } of ViewController.

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        func numberOfComponents(in pickerView: UIPickerView) -> Int {
            return 1
        }
    
        func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
            return categories.count
        }
    
  2. Add the UIPickerView delegate interface methods. This will map a request for a specific row to an element in the categories array. Once the user selects an row, a geocode will be performed for the places matching the selected category.

    Add these new methods after the data source methods added in the prior step.

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        func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
            return categories[row].title
        }
    
        func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
            findPlaces(forCategory: categories[row])
        }
    

Show information about a tapped location in the map

An identify operation can be used to get information about a geoelement (such as a graphic) at a location where the user has tapped on the map. A callout can be used to display this information.

  1. Add a method to respond to the AGSGeoViewTouchDelegate protocol. When the user taps the map, use the identify operation to determine if there is a result graphic at that location. An identify operation can return more than one result but you will show the first one.

    This method is called via the AGSGeoViewTouchDelegate protocol you set on the ViewController. When the user taps the map you are given the screen point and the corresponding map location.

    If a callout is open from a prior search, close it.

    Call identify on the map view to identify which graphics objects in the graphics overlay correspond with the screen point indicated by the user. If this identify operation returns results, call your showCalloutForGraphic method with the first graphic result identified and the corresponding map location.

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        func geoView(_ geoView: AGSGeoView, didTapAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {
    
            // Dismiss the callout if already visible.
            self.mapView.callout.dismiss()
    
            // Identify graphics at the tapped location.
            self.mapView.identify(self.graphicsOverlay, screenPoint: screenPoint, tolerance: 10, returnPopupsOnly: false, maximumResults: 2) { (result: AGSIdentifyGraphicsOverlayResult) -> Void in
                guard result.error == nil else {
                    print(result.error!)
                    return
                }
                if let graphic = result.graphics.first {
                    // Show a callout for the first graphic in the array.
                    self.showCalloutForGraphic(graphic, tapLocation: mapPoint)
                }
            }
        }
    
  2. Create a method to assign the location's attributes to the mapView.callout. Show the callout when the user taps a graphic on the map.

    An AGSCallout is a property of the AGSMapView. The location's name and address are passed to the title and detail string of the AGSCallout so they can be displayed when the user taps on a place.

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        // When a graphic in the graphics layer is tapped, use a callout to dislay its attributes.
        private func showCalloutForGraphic(_ graphic:AGSGraphic, tapLocation:AGSPoint) {
            self.mapView.callout.title = graphic.attributes["PlaceName"] as? String ?? "Unknown"
            self.mapView.callout.detail = graphic.attributes["Place_addr"] as? String ?? "no address provided"
            self.mapView.callout.isAccessoryButtonHidden = true
            self.mapView.callout.show(for: graphic, tapLocation: tapLocation, animated: true)
        }
    

Put it all together

Load the basemap, search for coffee shops in the visible area (using the first category in the Picker View), and display their location on the map.

  1. Update the setupMap method to display the .arcGISNavigation basemap style. Change the AGSViewpoint constructor to center the map around Malibu, California.

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        private func setupMap() {
    
            let map = AGSMap(
                basemapStyle: .arcGISNavigation
            )
            mapView.map = map
            mapView.setViewpoint(
                AGSViewpoint(
                    latitude: 34.09042,
                    longitude: -118.71511,
                    scale: 500_000
                )
            )
    
        }
    
  2. Add a touch delegate so that the app responds when the user taps on the map. Provide a graphics overlay to display the places on the map.

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        private func setupMap() {
    
            let map = AGSMap(
                basemapStyle: .arcGISNavigation
            )
            mapView.map = map
            mapView.setViewpoint(
                AGSViewpoint(
                    latitude: 34.09042,
                    longitude: -118.71511,
                    scale: 500_000
                )
            )
    
            mapView.touchDelegate = self
            mapView.graphicsOverlays.add(graphicsOverlay)
    
        }
    
  3. When the map finishes navigating to a new extent, perform a new search using the updated visible area. Add a key/value observer on the map view to listen for a change in isNavigating. Once map navigation completes, call findPlacesForCategoryPickerSelection.

    ViewController.swift
    Use dark colors for code blocks
                                                                                                                                                                                                          
    Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.
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        private func setupMap() {
    
            let map = AGSMap(
                basemapStyle: .arcGISNavigation
            )
            mapView.map = map
            mapView.setViewpoint(
                AGSViewpoint(
                    latitude: 34.09042,
                    longitude: -118.71511,
                    scale: 500_000
                )
            )
    
            mapView.touchDelegate = self
            mapView.graphicsOverlays.add(graphicsOverlay)
    
            // When the map finishes navigating to a new extent perform a new search using the updated visible area.
            isNavigatingObserver = mapView.observe(\.isNavigating, options:[]) { (mapView, _) in
    
                guard !mapView.isNavigating else { return }
    
                // Update results if the map view extent has moved.
                DispatchQueue.main.async { [weak self] in
                    self?.findPlacesForCategoryPickerSelection()
                }
            }
    
        }
    
  4. When the map view loads the first time, use the viewpointChangedHandler to perform a search on the selected category. The matching places are displayed on the map.

    Once the search is performed the first time, you no longer need this handler and can disable it.

    ViewController.swift
    Use dark colors for code blocks