Cut geometry

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Sample viewer app

Cut a geometry along a polyline.

Image of cut geometry

Use case

You might cut a polygon representing a large parcel to subdivide it into smaller parcels.

How to use the sample

Tap the button to cut the polygon with the polyline and see the resulting parts (shaded in different colors).

How it works

  1. Pass the geometry and polyline to class AGSGeometryEngine.cut(_:withCutter:) to cut the geometry along the polyline.
  2. Loop through the returned list of part geometries. Some of these geometries may be multi-part.

Relevant API

  • AGSPolygon
  • AGSPolyline
  • class AGSGeometryEngine.cut(_:withCutter:)

Tags

cut, geometry, split

Sample Code

CutGeometryViewController.swift
                                                                                                                                                      
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// Copyright 2018 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

class CutGeometryViewController: UIViewController {
    @IBOutlet weak var mapView: AGSMapView!

    let graphicsOverlay = AGSGraphicsOverlay()

    var lakeSuperiorPolygonGraphic: AGSGraphic = {
        // create an array of points that represents Lake Superior (polygon). Use the same spatial reference as the underlying base map
        let points = [
            AGSPoint(x: -10254374.668616, y: 5908345.076380, spatialReference: .webMercator()),
            AGSPoint(x: -10178382.525314, y: 5971402.386779, spatialReference: .webMercator()),
            AGSPoint(x: -10118558.923141, y: 6034459.697178, spatialReference: .webMercator()),
            AGSPoint(x: -9993252.729399, y: 6093474.872295, spatialReference: .webMercator()),
            AGSPoint(x: -9882498.222673, y: 6209888.368416, spatialReference: .webMercator()),
            AGSPoint(x: -9821057.766387, y: 6274562.532928, spatialReference: .webMercator()),
            AGSPoint(x: -9690092.583250, y: 6241417.023616, spatialReference: .webMercator()),
            AGSPoint(x: -9605207.742329, y: 6206654.660191, spatialReference: .webMercator()),
            AGSPoint(x: -9564786.389509, y: 6108834.986367, spatialReference: .webMercator()),
            AGSPoint(x: -9449989.747500, y: 6095091.726408, spatialReference: .webMercator()),
            AGSPoint(x: -9462116.153346, y: 6044160.821855, spatialReference: .webMercator()),
            AGSPoint(x: -9417652.665244, y: 5985145.646738, spatialReference: .webMercator()),
            AGSPoint(x: -9438671.768711, y: 5946341.148031, spatialReference: .webMercator()),
            AGSPoint(x: -9398250.415891, y: 5922088.336339, spatialReference: .webMercator()),
            AGSPoint(x: -9419269.519357, y: 5855797.317714, spatialReference: .webMercator()),
            AGSPoint(x: -9467775.142741, y: 5858222.598884, spatialReference: .webMercator()),
            AGSPoint(x: -9462924.580403, y: 5902686.086985, spatialReference: .webMercator()),
            AGSPoint(x: -9598740.325877, y: 5884092.264688, spatialReference: .webMercator()),
            AGSPoint(x: -9643203.813979, y: 5845287.765981, spatialReference: .webMercator()),
            AGSPoint(x: -9739406.633691, y: 5879241.702350, spatialReference: .webMercator()),
            AGSPoint(x: -9783061.694736, y: 5922896.763395, spatialReference: .webMercator()),
            AGSPoint(x: -9844502.151022, y: 5936640.023354, spatialReference: .webMercator()),
            AGSPoint(x: -9773360.570059, y: 6019099.583107, spatialReference: .webMercator()),
            AGSPoint(x: -9883306.649729, y: 5968977.105610, spatialReference: .webMercator()),
            AGSPoint(x: -9957681.938918, y: 5912387.211662, spatialReference: .webMercator()),
            AGSPoint(x: -10055501.612742, y: 5871965.858842, spatialReference: .webMercator()),
            AGSPoint(x: -10116942.069028, y: 5884092.264688, spatialReference: .webMercator()),
            AGSPoint(x: -10111283.079633, y: 5933406.315128, spatialReference: .webMercator()),
            AGSPoint(x: -10214761.742852, y: 5888134.399970, spatialReference: .webMercator()),
            AGSPoint(x: -10254374.668616, y: 5901877.659929, spatialReference: .webMercator())
        ]

        // create a polygon from the array of points
        let polygon = AGSPolygon(points: points)

        // create a blue border line symbol with a stroke weight of 4 for the Lake Superior polygon
        let lineSymbol = AGSSimpleLineSymbol(style: .solid, color: .blue, width: 4)

        // create a semi transparent blue fill symbol using the red border line symbol for the Lake Superior polygon
        let fillSymbol = AGSSimpleFillSymbol(style: .solid, color: #colorLiteral(red: 0, green: 0, blue: 1, alpha: 0.1), outline: lineSymbol)

        // create a graphic using the polyline and fill symbol for the border polyline
        let graphic = AGSGraphic(geometry: polygon, symbol: fillSymbol, attributes: nil)

        return graphic
    }()

    var borderPolylineGraphic: AGSGraphic = {
        // create an array of points that represents a cut line
        let points = [
            AGSPoint(x: -9981328.687124, y: 6111053.281447, spatialReference: .webMercator()),
            AGSPoint(x: -9946518.044066, y: 6102350.620682, spatialReference: .webMercator()),
            AGSPoint(x: -9872545.427566, y: 6152390.920079, spatialReference: .webMercator()),
            AGSPoint(x: -9838822.617103, y: 6157830.083057, spatialReference: .webMercator()),
            AGSPoint(x: -9446115.050097, y: 5927209.572793, spatialReference: .webMercator()),
            AGSPoint(x: -9430885.393759, y: 5876081.440801, spatialReference: .webMercator()),
            AGSPoint(x: -9415655.737420, y: 5860851.784463, spatialReference: .webMercator())
        ]

        // create a polyline from the array of points
        let polyline = AGSPolyline(points: points)

        // create a red border line symbol with a stroke weight of 5
        let lineSymbol = AGSSimpleLineSymbol(style: .dot, color: .red, width: 5)

        // create a graphic using the polyline and line symbol for the border polyline
        let graphic = AGSGraphic(geometry: polyline, symbol: lineSymbol, attributes: nil)

        return graphic
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        // add the source code button item to the right of navigation bar
        (self.navigationItem.rightBarButtonItem as! SourceCodeBarButtonItem).filenames = ["CutGeometryViewController"]

        // instantiate map using basemap
        let map = AGSMap(basemapStyle: .arcGISTopographic)

        // assign map to the map view
        mapView.map = map

        // add lake superior polygon graphic and border polyline graphic to graphics overlay
        graphicsOverlay.graphics.addObjects(from: [lakeSuperiorPolygonGraphic, borderPolylineGraphic])

        // add graphics overlay to map view
        mapView.graphicsOverlays.add(graphicsOverlay)

        // set viewpoint to the extent of the Lake Superior polygon
        mapView.setViewpointGeometry(lakeSuperiorPolygonGraphic.geometry!, completion: nil)
    }

    @IBAction func cutGeometryWithPolyline(_ sender: Any) {
        // disable the cut button
        (sender as? UIBarButtonItem)?.isEnabled = false

        // cut the Lake Superior polygon using the border polyline
        guard let parts = AGSGeometryEngine.cut(lakeSuperiorPolygonGraphic.geometry!, withCutter: borderPolylineGraphic.geometry! as! AGSPolyline),
            parts.count >= 2 else {
            return
        }

        // create a null border line symbol for the newly cut Canada polygon
        let canadaLineSymbol = AGSSimpleLineSymbol(style: .null, color: .clear, width: 0)

        // create a green backward diagonal fill symbol for the newly cut Canada polygon
        let canadaFillSymbol = AGSSimpleFillSymbol(style: .backwardDiagonal, color: .green, outline: canadaLineSymbol)

        // create a Canada graphic using the polygon and line symbol
        let canadaSide = AGSGraphic(geometry: parts[0], symbol: canadaFillSymbol, attributes: nil)

        // create a null border line symbol for the newly cut USA polygon
        let usaLineSymbol = AGSSimpleLineSymbol(style: .null, color: .clear, width: 0)

        // create a yellow forward diagonal fill symbol for the newly cut USA polygon
        let usaFillSymbol = AGSSimpleFillSymbol(style: .forwardDiagonal, color: .yellow, outline: usaLineSymbol)

        // create a USA graphic using the polygon and line symbol
        let usaSide = AGSGraphic(geometry: parts[1], symbol: usaFillSymbol, attributes: nil)

        // add new graphics to graphics overlay
        graphicsOverlay.graphics.addObjects(from: [canadaSide, usaSide])
    }
}

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