Custom Query

1-query.swift

public enum QueryError: LocalizedError {
    case couldNotParseJSON
    case unexpectedJSONResponse
}

func doQuery(layerURL: URL, mapPoint: AGSPoint, fields: [String] = ["*"], returnGeometry: Bool = true, completion: (([AGSGraphic]?, Error?) -> Void)? = nil) {
    var mapPointData: Data?
    do {
        let mapPointJSON = try mapPoint.toJSON()
        mapPointData = try JSONSerialization.data(withJSONObject: mapPointJSON)
    } catch {
        print("Could not convert AGSPoint to JSON: \(error.localizedDescription)")
        completion?(nil, error)
        return
    }
    
    guard mapPointData != nil,
        let mapPointJSONString = String(data: mapPointData!, encoding: .utf8) else {
            completion?(nil, QueryError.couldNotParseJSON)
            return
    }
    
    let inSR = mapPoint.spatialReference ?? AGSSpatialReference.webMercator()
    let outSR = mapView.spatialReference ?? AGSSpatialReference.webMercator()
    
    let parameters: [String : Any] = [
        "f": "json",
        "geometry": mapPointJSONString,
        "geometryType": "esriGeometryPoint",
        "inSR":  inSR.wkid,
        "maxAllowableOffset": 0.000000,
        "outFields": fields.joined(separator: ","),
        "outSR": outSR.wkid,
        "returnDistinctValues": false,
        "returnGeometry": returnGeometry,
        "returnM": true,
        "returnZ": true,
        "spatialRel": "esriSpatialRelIntersects"
    ]
    
    let queryUrl = layerURL.appendingPathComponent("query")
    let operation = AGSJSONRequestOperation(remoteResource: nil, url: queryUrl, queryParameters: parameters)
    
    operation.registerListener(self) { (result, error) in
        if let error = error {
            print("Error performing query! \(error.localizedDescription)")
            completion?(nil, error)
            return
        }
        
        guard let result = result as? [String: Any],
            let fields = (result["fields"] as? [Any])?.compactMap({ try? AGSField.fromJSON($0) as? AGSField }),
            let graphics = (result["features"] as? [[String: Any]])?.compactMap({ data -> AGSGraphic? in
                let attributes = data["attributes"] as? [String: Any]
                let geometry: AGSGeometry? = {
                    if let geomDict = data["geometry"] as? [String: Any] {
                        let geom = try? AGSGeometry.fromJSON(geomDict) as? AGSGeometry
                        if let geom = geom, geom.spatialReference == nil {
                            // Bit of a hack to force an SR onto the empty geometry
                            return AGSGeometryEngine.projectGeometry(geom, to: outSR)
                        }
                        return geom
                    }
                    return nil
                }()
                if attributes == nil && geometry == nil { return nil }
                return AGSGraphic(geometry: geometry, symbol: nil, attributes: attributes)
            }) else
        {
            print("Result is not a dictionary. Hmm")
            completion?(nil, QueryError.unexpectedJSONResponse)
            return
        }
        
        completion?(graphics, nil)
    }
    
    #if DEBUG
    if let rc = AGSRequestConfiguration.global().copy() as? AGSRequestConfiguration {
        rc.debugLogRequests = true
        rc.debugLogResponses = true
        operation.requestConfiguration = rc
    }
    #endif
    
    AGSOperationQueue.shared().addOperation(operation)
}

2-callQuery.swift

let layer: AGSArcGISMapImageLayer = {
    let l = AGSArcGISMapImageLayer(url: URL(string: "https://demographics9.arcgis.com/arcgis/rest/services/USA_Demographics_and_Boundaries_2019/MapServer")!)
    l.credential = AGSCredential(user: "<username>", password: "<password>")
    return l
}()

let layerId = 49

// Only want to query if we're tapping on a visible layer.
guard layer.loadStatus == .loaded,
    layer.subLayerContents.count > layerId,
    let scale = mapView.currentViewpoint(with: .centerAndScale)?.targetScale,
    layer.subLayerContents[layerId].isVisible(atScale: scale),
    let subLayerURL = layer.url?.appendingPathComponent("\(layerId)") else { return }

doQuery(layerURL: subLayerURL, mapPoint: mapPoint,
        fields: ["OBJECTID", "NAME"], returnGeometry: true) { graphics, error in
    if let error = error {
        print("Error during query: \(error.localizedDescription)")
        return
    }
    
    guard let graphics = graphics else {
        print("Something went wrong during the query")
        return
    }

    print("Got \(graphics.count) graphics back!")
}