Show and hide a layer | Maps SDK v6 | iOS

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This page uses v6.4.1 of the Mapbox Maps SDK. A newer version of the SDK is available. Learn about the latest version, v11.3.0, in the Maps SDK documentation.
Related example: custom raster source.
ViewController
github View on GitHub
Swift
Objective-C
import Mapbox

class ViewController: UIViewController, MGLMapViewDelegate {
    var mapView: MGLMapView!
    var contoursLayer: MGLStyleLayer?

    override func viewDidLoad() {
        super.viewDidLoad()

        mapView = MGLMapView(frame: view.bounds)
        mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

        mapView.setCenter(CLLocationCoordinate2D(latitude: 37.745395, longitude: -119.594421), zoomLevel: 11, animated: false)
        view.addSubview(mapView)

        addToggleButton()

        mapView.delegate = self
    }

    // Wait until the style is loaded before modifying the map style
    func mapView(_ mapView: MGLMapView, didFinishLoading style: MGLStyle) {
        addLayer(to: style)
    }

    func addLayer(to style: MGLStyle) {
        let source = MGLVectorTileSource(identifier: "contours", configurationURL: NSURL(string: "mapbox://mapbox.mapbox-terrain-v2")! as URL)

        let layer = MGLLineStyleLayer(identifier: "contours", source: source)
        layer.sourceLayerIdentifier = "contour"
        layer.lineJoin = NSExpression(forConstantValue: "round")
        layer.lineCap = NSExpression(forConstantValue: "round")
        layer.lineColor = NSExpression(forConstantValue: UIColor.brown)
        layer.lineWidth = NSExpression(forConstantValue: 1.0)

        style.addSource(source)
        if let water = style.layer(withIdentifier: "water") {
            // You can insert a layer below an existing style layer
            style.insertLayer(layer, below: water)
        } else {
            // or you can simply add it above all layers
            style.addLayer(layer)
        }

        self.contoursLayer = layer

        showContours()
    }

    @objc func toggleLayer(sender: UIButton) {
        sender.isSelected = !sender.isSelected
        if sender.isSelected {
            showContours()
        } else {
            hideContours()
        }
    }

    func showContours() {
        self.contoursLayer?.isVisible = true
    }

    func hideContours() {
        self.contoursLayer?.isVisible = false
    }

    func addToggleButton() {
        let button = UIButton(type: .system)
        button.setTitle("Toggle Contours", for: .normal)
        button.isSelected = true
        button.sizeToFit()
        button.center.x = self.view.center.x
        button.frame = CGRect(origin: CGPoint(x: button.frame.origin.x, y: self.view.frame.size.height - button.frame.size.height - 5), size: button.frame.size)
        button.addTarget(self, action: #selector(toggleLayer(sender:)), for: .touchUpInside)
        self.view.addSubview(button)

        if #available(iOS 11.0, *) {
            let safeArea = view.safeAreaLayoutGuide
            button.translatesAutoresizingMaskIntoConstraints = false
            let constraints = [
                button.bottomAnchor.constraint(equalTo: safeArea.bottomAnchor, constant: -5),
                button.centerXAnchor.constraint(equalTo: safeArea.centerXAnchor)
            ]

            NSLayoutConstraint.activate(constraints)
        } else {
            button.autoresizingMask = [.flexibleTopMargin, .flexibleLeftMargin, .flexibleRightMargin]
        }
    }
}