Create a feature collection layer to show a query result from a service feature table.
Use case
Consider a national wireless telecommunications company who wants to improve connectivity within areas of poor coverage. Their cell towers, cell tower radii and state boundaries data are held within service feature tables, which can be queried for states that don't meet a certain threshold of coverage. The query result can be used to create and display a single feature collection layer for analysis of areas requiring improved coverage.
How to use the sample
When launched, this sample displays a map with point features as a feature collection layer. Pan and zoom to explore the map.
How it works
Perform a query using the AGSFeatureTable.queryFeatures(with:completion:) method on an AGSServiceFeatureTable.
Create an AGSFeatureCollectionTable with the AGSFeatureQueryResult.
Create an AGSFeatureCollection and add the feature collection table to it.
Create an AGSFeatureCollectionLayer from the feature collection.
Add the feature collection layer to the map's operationalLayers array.
Relevant API
AGSFeatureCollection
AGSFeatureCollectionLayer
AGSFeatureCollectionTable
AGSFeatureLayer
AGSFeatureQueryResult
AGSFeatureTable
AGSQueryParameters
AGSServiceFeatureTable
About the data
This application utilizes data from the wildfire feature service. It loads at full extent with features indicating wildfire response point features across the world.
Tags
layer, query, search, table
Sample Code
FeatureCollectionLayerQueryViewController.swift
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//// Copyright 2017 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
classFeatureCollectionLayerQueryViewController: UIViewController{
@IBOutletvar mapView: AGSMapView!
privatevar featureTable: AGSServiceFeatureTable!
overridefuncviewDidLoad() {
super.viewDidLoad()
// add the source code button item to the right of navigation bar (self.navigationItem.rightBarButtonItem as!SourceCodeBarButtonItem).filenames = ["FeatureCollectionLayerQueryViewController"]
// initialize map with basemaplet map =AGSMap(basemapStyle: .arcGISOceans)
// assign map to the map viewself.mapView.map = map
// initialize service feature table to be queriedself.featureTable =AGSServiceFeatureTable(url: URL(string: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/Wildfire/FeatureServer/0")!)
// create query parameterslet queryParams =AGSQueryParameters()
// 1=1 will give all the features from the table queryParams.whereClause ="1=1"// show progress hudUIApplication.shared.showProgressHUD(message: "Querying")
// query feature from the tableself.featureTable.queryFeatures(with: queryParams) { [weakself] (queryResult: AGSFeatureQueryResult?, error: Error?) in// hide progress hudUIApplication.shared.hideProgressHUD()
iflet error = error {
// show errorself?.presentAlert(error: error)
} else {
// create a feature collection table fromt the query resultslet featureCollectionTable =AGSFeatureCollectionTable(featureSet: queryResult!)
// create a feature collection from the above feature collection tablelet featureCollection =AGSFeatureCollection(featureCollectionTables: [featureCollectionTable])
// create a feature collection layerlet featureCollectionLayer =AGSFeatureCollectionLayer(featureCollection: featureCollection)
// add the layer to the operational layers arrayself?.mapView.map?.operationalLayers.add(featureCollectionLayer)
}
}
}
}