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Custom Turns ID

Last updated: April 7, 2026 | 2 minutes read

This example demonstrates how to use GEMKit in a UIKit application to replace the default SDK turn icons with custom images keyed by the numeric TurnId64 value of each upcoming manoeuvre.

Check the full implementation on GitHub.

Custom Turns ID

UI and Map Integration​

The view controller uses GEMSdkDelegate to gate the route button on connectivity and map availability. The camera focus point is moved down so the vehicle position appears centred in the lower portion of the screen during simulation:

ViewController.swiftView on GitHub
class ViewController: UIViewController, GEMSdkDelegate, MapViewControllerDelegate, NavigationContextDelegate {

    var mapViewController: MapViewController?
    var navigationContext: NavigationContext?
    var soundContext: SoundContext?
    var panelNavigationViewController: NavigationViewController?

    override func viewDidLoad() {

        super.viewDidLoad()

        GEMSdk.shared().delegate = self

        self.title = "Custom Turn ID"

        self.createMapView()
        self.addRouteButton()
        self.setFollowPositionCameraFocus()
    }

    func setFollowPositionCameraFocus() {

        guard let mapViewController = self.mapViewController else { return }

        let point = CGPoint.init(x: 0.5, y: 0.75)

        mapViewController.getPreferences().getFollowPositionPreferences().setCameraFocus(point)
    }

Rendering Custom Turn Images by ID​

During simulation, updateCustomTurnInformation retrieves the TurnId64 integer for both the next and next-next manoeuvres and loads a matching image from the app bundle:

info

The set of 64 turn icons are added as image assets to the app bundle with their names set to the corresponding integer value.

NavigationViewController.swiftView on GitHub
    func updateCustomTurnInformation(navigationContext: NavigationContext) {

        if let turnInstruction = navigationContext.getNavigationInstruction() {

            if let nextTurnDetails = turnInstruction.getNextTurnDetails() {

                let turnId64 = nextTurnDetails.getTurnId64()

                if let image = UIImage(named: String(format: "%d", turnId64.rawValue)) {

                    self.customTurnNextImage.image = image
                    self.customTurnNextImage.isHidden = false
                }
            }

            if let nextNextTurnDetails = turnInstruction.getNextNextTurnDetails() {

                let turnId64 = nextNextTurnDetails.getTurnId64()

                if let image = UIImage(named: String(format: "%d", turnId64.rawValue)) {

                    self.customTurnNextNextImage.image = image
                    self.customTurnNextNextImage.isHidden = false
                }
            }
        }
    }
info

The NavigationViewController used in this example extends the standard turn-by-turn panel with two extra image views that display the custom turn ID icons. Due to its size it is not reproduced here — check the full implementation on GitHub.

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