Customize the user location annotation

This example uses two classes within a single file:

import Mapbox
class ViewController: UIViewController, MGLMapViewDelegate {
let point = MGLPointAnnotation()
override func viewDidLoad() {
super.viewDidLoad()
let mapView = MGLMapView(frame: view.bounds)
mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
mapView.delegate = self
// Enable heading tracking mode so that the arrow will appear.
mapView.userTrackingMode = .followWithHeading
// Enable the permanent heading indicator, which will appear when the tracking mode is not `.followWithHeading`.
mapView.showsUserHeadingIndicator = true
view.addSubview(mapView)
}
func mapView(_ mapView: MGLMapView, viewFor annotation: MGLAnnotation) -> MGLAnnotationView? {
// Substitute our custom view for the user location annotation. This custom view is defined below.
if annotation is MGLUserLocation && mapView.userLocation != nil {
return CustomUserLocationAnnotationView()
}
return nil
}
// Optional: tap the user location annotation to toggle heading tracking mode.
func mapView(_ mapView: MGLMapView, didSelect annotation: MGLAnnotation) {
if mapView.userTrackingMode != .followWithHeading {
mapView.userTrackingMode = .followWithHeading
} else {
mapView.resetNorth()
}
// We're borrowing this method as a gesture recognizer, so reset selection state.
mapView.deselectAnnotation(annotation, animated: false)
}
}
// Create a subclass of MGLUserLocationAnnotationView.
class CustomUserLocationAnnotationView: MGLUserLocationAnnotationView {
let size: CGFloat = 48
var dot: CALayer!
var arrow: CAShapeLayer!
// -update is a method inherited from MGLUserLocationAnnotationView. It updates the appearance of the user location annotation when needed. This can be called many times a second, so be careful to keep it lightweight.
override func update() {
if frame.isNull {
frame = CGRect(x: 0, y: 0, width: size, height: size)
return setNeedsLayout()
}
// Check whether we have the user’s location yet.
if CLLocationCoordinate2DIsValid(userLocation!.coordinate) {
setupLayers()
updateHeading()
}
}
private func updateHeading() {
// Show the heading arrow, if the heading of the user is available.
if let heading = userLocation!.heading?.trueHeading {
arrow.isHidden = false
// Get the difference between the map’s current direction and the user’s heading, then convert it from degrees to radians.
let rotation: CGFloat = -MGLRadiansFromDegrees(mapView!.direction - heading)
// If the difference would be perceptible, rotate the arrow.
if fabs(rotation) > 0.01 {
// Disable implicit animations of this rotation, which reduces lag between changes.
CATransaction.begin()
CATransaction.setDisableActions(true)
arrow.setAffineTransform(CGAffineTransform.identity.rotated(by: rotation))
CATransaction.commit()
}
} else {
arrow.isHidden = true
}
}
private func setupLayers() {
// This dot forms the base of the annotation.
if dot == nil {
dot = CALayer()
dot.bounds = CGRect(x: 0, y: 0, width: size, height: size)
// Use CALayer’s corner radius to turn this layer into a circle.
dot.cornerRadius = size / 2
dot.backgroundColor = super.tintColor.cgColor
dot.borderWidth = 4
dot.borderColor = UIColor.white.cgColor
layer.addSublayer(dot)
}
// This arrow overlays the dot and is rotated with the user’s heading.
if arrow == nil {
arrow = CAShapeLayer()
arrow.path = arrowPath()
arrow.frame = CGRect(x: 0, y: 0, width: size / 2, height: size / 2)
arrow.position = CGPoint(x: dot.frame.midX, y: dot.frame.midY)
arrow.fillColor = dot.borderColor
layer.addSublayer(arrow)
}
}
// Calculate the vector path for an arrow, for use in a shape layer.
private func arrowPath() -> CGPath {
let max: CGFloat = size / 2
let pad: CGFloat = 3
let top = CGPoint(x: max * 0.5, y: 0)
let left = CGPoint(x: 0 + pad, y: max - pad)
let right = CGPoint(x: max - pad, y: max - pad)
let center = CGPoint(x: max * 0.5, y: max * 0.6)
let bezierPath = UIBezierPath()
bezierPath.move(to: top)
bezierPath.addLine(to: left)
bezierPath.addLine(to: center)
bezierPath.addLine(to: right)
bezierPath.addLine(to: top)
bezierPath.close()
return bezierPath.cgPath
}
}