Render features in a layer using a distinct symbol for each unique attribute value.
Use case
A unique value renderer allows you to symbolize features in a layer based on one or more matching attributes. This is typically done by using unique colors, fill styles, or images to represent features with equal values in a string field. A unique value renderer could be used to show different types of trees on a vegetation map by using symbols corresponding to matching name attributes.
How to use the sample
The map with the symbolized feature layer will be shown automatically when the sample loads.
How it works
Using the AGSUniqueValueRenderer, separate symbols can be used to display features that have a specific value for a given field. In this case, the field is subregions of the USA. While multiple fields can be used, this sample only uses one.
An AGSSimpleFillSymbol is defined for each type of feature.
AGSSimpleFillSymbol can be applied to polygon features, which is the type of feature contained by this AGSServiceFeatureTable.
Separate AGSUniqueValue objects are created which define the values in the renderer field and the symbol used to render matching features.
A default symbol is created to render all features that do not match any of the AGSUniqueValue objects defined.
Relevant API
AGSFeatureLayer
AGSServiceFeatureTable
AGSSimpleFillSymbol
AGSSimpleLineSymbol
AGSUniqueValue
AGSUniqueValueRenderer
About the data
The map shows U.S. states symbolized by subregion. Symbols are defined for Pacific, Mountain, and West South Central states. All other features are symbolized with the default symbol.
Tags
draw, renderer, symbol, symbology, values
Sample Code
UniqueValueRendererViewController.swift
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//// Copyright 2016 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
/// A view controller that manages the interface of the Unique Value Renderer/// sample.classUniqueValueRendererViewController: UIViewController{
/// The map view managed by the view controller.@IBOutletvar mapView: AGSMapView! {
didSet {
// assign map to the map view mapView.map = makeMap()
// set initial viewpointlet center =AGSPoint(x: -12966000.5, y: 4441498.5, spatialReference: .webMercator())
mapView.setViewpoint(AGSViewpoint(center: center, scale: 4e7))
}
}
/// Creates a map with a feature layer configured with a unique value/// renderer.////// - Returns: A new `AGSMap` object.funcmakeMap() -> AGSMap {
// instantiate map with basemaplet map =AGSMap(basemapStyle: .arcGISTopographic)
// create feature layerlet featureTable =AGSServiceFeatureTable(url: URL(string: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/3")!)
let featureLayer =AGSFeatureLayer(featureTable: featureTable)
// make unique value renderer and assign it to the feature layer featureLayer.renderer = makeUniqueValueRenderer()
// add the layer to the map as operational layer map.operationalLayers.add(featureLayer)
return map
}
/// Creates a unique value renderer configured to render California as red,/// Arizona as green, and Nevada as blue.////// - Returns: A new `AGSUniqueValueRenderer` object.funcmakeUniqueValueRenderer() -> AGSUniqueValueRenderer {
// instantiate a new unique value rendererlet renderer =AGSUniqueValueRenderer()
// set the field to use for the unique values// You can add multiple fields to be used for the renderer in the form of a list, in this case we are only adding a single field renderer.fieldNames = ["STATE_ABBR"]
// create symbols to be used in the rendererlet defaultSymbol =AGSSimpleFillSymbol(style: .null, color: .clear, outline: AGSSimpleLineSymbol(style: .solid, color: .gray, width: 2))
let californiaSymbol =AGSSimpleFillSymbol(style: .solid, color: .red, outline: AGSSimpleLineSymbol(style: .solid, color: .red, width: 2))
let arizonaSymbol =AGSSimpleFillSymbol(style: .solid, color: .green, outline: AGSSimpleLineSymbol(style: .solid, color: .green, width: 2))
let nevadaSymbol =AGSSimpleFillSymbol(style: .solid, color: .blue, outline: AGSSimpleLineSymbol(style: .solid, color: .blue, width: 2))
// set the default symbol renderer.defaultSymbol = defaultSymbol
renderer.defaultLabel ="Other"// create unique valueslet californiaValue =AGSUniqueValue(description: "State of California", label: "California", symbol: californiaSymbol, values: ["CA"])
let arizonaValue =AGSUniqueValue(description: "State of Arizona", label: "Arizona", symbol: arizonaSymbol, values: ["AZ"])
let nevadaValue =AGSUniqueValue(description: "State of Nevada", label: "Nevada", symbol: nevadaSymbol, values: ["NV"])
// add the values to the renderer renderer.uniqueValues.append(contentsOf: [californiaValue, arizonaValue, nevadaValue])
return renderer
}
// MARK: UIViewControlleroverridefuncviewDidLoad() {
super.viewDidLoad()
// add the source code button item to the right of navigation bar (self.navigationItem.rightBarButtonItem as!SourceCodeBarButtonItem).filenames = ["UniqueValueRendererViewController"]
}
}