231 lines
11 KiB
Swift
231 lines
11 KiB
Swift
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import MapLibre
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import SwiftUI
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import UIKit
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// #-example-code(WebAPIDataExample)
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class WebAPIDataExample: UIViewController, MLNMapViewDelegate {
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var mapView: MLNMapView!
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override func viewDidLoad() {
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super.viewDidLoad()
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mapView = MLNMapView(frame: view.bounds)
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mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
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mapView.setCenter(CLLocationCoordinate2D(latitude: 37.090240, longitude: -95.712891), zoomLevel: 2, animated: false)
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mapView.delegate = self
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mapView.attributionButton.isHidden = true
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view.addSubview(mapView)
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// Add a single tap gesture recognizer. This gesture requires the built-in MLNMapView tap gestures (such as those for zoom and annotation selection) to fail.
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let singleTap = UITapGestureRecognizer(target: self, action: #selector(handleMapTap(sender:)))
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for recognizer in mapView.gestureRecognizers! where recognizer is UITapGestureRecognizer {
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singleTap.require(toFail: recognizer)
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}
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mapView.addGestureRecognizer(singleTap)
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}
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func mapView(_: MLNMapView, didFinishLoading _: MLNStyle) {
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fetchPoints { [weak self] features in
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self?.addItemsToMap(features: features)
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}
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}
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func addItemsToMap(features: [MLNPointFeature]) {
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// MLNMapView.style is optional, so you must guard against it not being set.
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guard let style = mapView.style else { return }
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// You can add custom UIImages to the map style.
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// These can be referenced by an MLNSymbolStyleLayer’s iconImage property.
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style.setImage(UIImage(named: "lighthouse")!, forName: "lighthouse")
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// Add the features to the map as a shape source.
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let source = MLNShapeSource(identifier: "us-lighthouses", features: features, options: nil)
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style.addSource(source)
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let lighthouseColor = UIColor(red: 0.08, green: 0.44, blue: 0.96, alpha: 1.0)
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// Use MLNCircleStyleLayer to represent the points with simple circles.
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// In this case, we can use style functions to gradually change properties between zoom level 2 and 7: the circle opacity from 50% to 100% and the circle radius from 2pt to 3pt.
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let circles = MLNCircleStyleLayer(identifier: "lighthouse-circles", source: source)
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circles.circleColor = NSExpression(forConstantValue: lighthouseColor)
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// The circles should increase in opacity from 0.5 to 1 based on zoom level.
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circles.circleOpacity = NSExpression(forMLNInterpolating: NSExpression.zoomLevelVariable, curveType: MLNExpressionInterpolationMode.linear, parameters: nil, stops: NSExpression(forConstantValue: [2: 0.5, 7: 1]))
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circles.circleRadius = NSExpression(forMLNInterpolating: NSExpression.zoomLevelVariable, curveType: MLNExpressionInterpolationMode.linear, parameters: nil, stops: NSExpression(forConstantValue: [2: 2, 7: 3]))
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// Use MLNSymbolStyleLayer for more complex styling of points including custom icons and text rendering.
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let symbols = MLNSymbolStyleLayer(identifier: "lighthouse-symbols", source: source)
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symbols.iconImageName = NSExpression(forConstantValue: "lighthouse")
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symbols.iconColor = NSExpression(forConstantValue: lighthouseColor)
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symbols.iconScale = NSExpression(forConstantValue: 0.5)
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symbols.iconHaloColor = NSExpression(forConstantValue: UIColor.white.withAlphaComponent(0.5))
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symbols.iconHaloWidth = NSExpression(forConstantValue: 1)
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symbols.iconOpacity = NSExpression(forMLNInterpolating: NSExpression.zoomLevelVariable, curveType: MLNExpressionInterpolationMode.linear, parameters: nil, stops: NSExpression(forConstantValue: [5.9: 0, 6: 1]))
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// "name" references the "name" key in an MLNPointFeature’s attributes dictionary.
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symbols.text = NSExpression(forKeyPath: "name")
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symbols.textColor = symbols.iconColor
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symbols.textFontSize = NSExpression(forMLNInterpolating: NSExpression.zoomLevelVariable, curveType: MLNExpressionInterpolationMode.linear, parameters: nil, stops: NSExpression(forConstantValue: [10: 10, 16: 16]))
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symbols.textTranslation = NSExpression(forConstantValue: NSValue(cgVector: CGVector(dx: 15, dy: 0)))
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symbols.textOpacity = symbols.iconOpacity
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symbols.textHaloColor = symbols.iconHaloColor
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symbols.textHaloWidth = symbols.iconHaloWidth
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symbols.textJustification = NSExpression(forConstantValue: NSValue(mlnTextJustification: .left))
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symbols.textAnchor = NSExpression(forConstantValue: NSValue(mlnTextAnchor: .left))
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style.addLayer(circles)
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style.addLayer(symbols)
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}
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// MARK: - Feature interaction
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@IBAction func handleMapTap(sender: UITapGestureRecognizer) {
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if sender.state == .ended {
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// Limit feature selection to just the following layer identifiers.
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let layerIdentifiers: Set = ["lighthouse-symbols", "lighthouse-circles"]
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// Try matching the exact point first.
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let point = sender.location(in: sender.view!)
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for feature in mapView.visibleFeatures(at: point, styleLayerIdentifiers: layerIdentifiers)
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where feature is MLNPointFeature
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{
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guard let selectedFeature = feature as? MLNPointFeature else {
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fatalError("Failed to cast selected feature as MLNPointFeature")
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}
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showCallout(feature: selectedFeature)
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return
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}
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let touchCoordinate = mapView.convert(point, toCoordinateFrom: sender.view!)
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let touchLocation = CLLocation(latitude: touchCoordinate.latitude, longitude: touchCoordinate.longitude)
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// Otherwise, get all features within a rect the size of a touch (44x44).
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let touchRect = CGRect(origin: point, size: .zero).insetBy(dx: -22.0, dy: -22.0)
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let possibleFeatures = mapView.visibleFeatures(in: touchRect, styleLayerIdentifiers: Set(layerIdentifiers)).filter { $0 is MLNPointFeature }
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// Select the closest feature to the touch center.
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let closestFeatures = possibleFeatures.sorted(by: {
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CLLocation(latitude: $0.coordinate.latitude, longitude: $0.coordinate.longitude).distance(from: touchLocation) < CLLocation(latitude: $1.coordinate.latitude, longitude: $1.coordinate.longitude).distance(from: touchLocation)
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})
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if let feature = closestFeatures.first {
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guard let closestFeature = feature as? MLNPointFeature else {
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fatalError("Failed to cast selected feature as MLNPointFeature")
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}
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showCallout(feature: closestFeature)
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return
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}
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// If no features were found, deselect the selected annotation, if any.
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mapView.deselectAnnotation(mapView.selectedAnnotations.first, animated: true)
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}
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}
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func showCallout(feature: MLNPointFeature) {
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let point = MLNPointFeature()
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point.title = feature.attributes["name"] as? String
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point.coordinate = feature.coordinate
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// Selecting an feature that doesn’t already exist on the map will add a new annotation view.
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// We’ll need to use the map’s delegate methods to add an empty annotation view and remove it when we’re done selecting it.
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mapView.selectAnnotation(point, animated: true, completionHandler: nil)
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}
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// MARK: - MLNMapViewDelegate
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func mapView(_: MLNMapView, annotationCanShowCallout _: MLNAnnotation) -> Bool {
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true
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}
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func mapView(_ mapView: MLNMapView, didDeselect annotation: MLNAnnotation) {
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mapView.removeAnnotations([annotation])
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}
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func mapView(_: MLNMapView, viewFor _: MLNAnnotation) -> MLNAnnotationView? {
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// Create an empty view annotation. Set a frame to offset the callout.
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MLNAnnotationView(frame: CGRect(x: 0, y: 0, width: 20, height: 20))
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}
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// MARK: - Data fetching and parsing
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func fetchPoints(withCompletion completion: @escaping (([MLNPointFeature]) -> Void)) {
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// Wikidata query for all lighthouses in the United States: http://tinyurl.com/zrl2jc4
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let query = "SELECT DISTINCT ?item " +
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"?itemLabel ?coor ?image " +
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"WHERE " +
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"{ " +
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"?item wdt:P31 wd:Q39715 . " +
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"?item wdt:P17 wd:Q30 . " +
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"?item wdt:P625 ?coor . " +
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"OPTIONAL { ?item wdt:P18 ?image } . " +
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"SERVICE wikibase:label { bd:serviceParam wikibase:language \"en\" } " +
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"} " +
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"ORDER BY ?itemLabel"
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let characterSet = NSMutableCharacterSet()
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characterSet.formUnion(with: CharacterSet.urlQueryAllowed)
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characterSet.removeCharacters(in: "?")
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characterSet.removeCharacters(in: "&")
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characterSet.removeCharacters(in: ":")
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let encodedQuery = query.addingPercentEncoding(withAllowedCharacters: characterSet as CharacterSet)!
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let request = URLRequest(url: URL(string: "https://query.wikidata.org/sparql?query=\(encodedQuery)&format=json")!)
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URLSession.shared.dataTask(with: request, completionHandler: { data, _, error in
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guard error == nil else {
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preconditionFailure("Failed to load GeoJSON data: \(error!)")
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}
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guard
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let data,
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let json = try? JSONSerialization.jsonObject(with: data, options: []) as? [String: AnyObject],
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let results = json["results"] as? [String: AnyObject],
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let items = results["bindings"] as? [[String: AnyObject]]
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else {
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preconditionFailure("Failed to parse GeoJSON data")
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}
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DispatchQueue.main.async {
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completion(self.parseJSONItems(items: items))
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}
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}).resume()
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}
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func parseJSONItems(items: [[String: AnyObject]]) -> [MLNPointFeature] {
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var features = [MLNPointFeature]()
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for item in items {
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guard let label = item["itemLabel"] as? [String: AnyObject],
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let title = label["value"] as? String else { continue }
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guard let coor = item["coor"] as? [String: AnyObject],
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let point = coor["value"] as? String else { continue }
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let parsedPoint = point.replacingOccurrences(of: "Point(", with: "").replacingOccurrences(of: ")", with: "")
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let pointComponents = parsedPoint.components(separatedBy: " ")
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let coordinate = CLLocationCoordinate2D(latitude: Double(pointComponents[1])!, longitude: Double(pointComponents[0])!)
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let feature = MLNPointFeature()
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feature.coordinate = coordinate
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feature.title = title
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// A feature’s attributes can used by runtime styling for things like text labels.
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feature.attributes = [
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"name": title,
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]
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features.append(feature)
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}
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return features
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}
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}
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// #-end-example-code
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struct WebAPIDataExampleUIViewControllerRepresentable: UIViewControllerRepresentable {
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typealias UIViewControllerType = WebAPIDataExample
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func makeUIViewController(context _: Context) -> WebAPIDataExample {
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WebAPIDataExample()
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}
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func updateUIViewController(_: WebAPIDataExample, context _: Context) {}
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}
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