iOS MapKit Custom User location heading wrong - swift

Question

I am trying to make a custom "user location" pin, with heading rotation based on users location heading.
I used this answer: https://stackoverflow.com/a/58363556/894671 as a base and managed to get up and running a custom pin, that rotates based on the heading.
The problem:
While testing on a device, it seems, that the transformation using the provided heading is not correct.
Only at 0/360 degrees it shows up correctly, but If I rotate around, I am seeing default MKMapKit shown heading to be correctly rotating, while my custom icon manages to rotate twice in that same time.
Please see the attached video:
https://i.imgur.com/3PEm2MS.mp4
Demo uploaded here:
https://github.com/GuntisTreulands/Demo123
But for all intents and purposes, here is AnnotationView:
class AnnotationView : MKAnnotationView, HeadingDelegate {
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override init(annotation: MKAnnotation?, reuseIdentifier: String?) {
super.init(annotation: annotation, reuseIdentifier: reuseIdentifier)
}
func headingChanged(_ heading: CLLocationDirection) {
// For simplicity the affine transform is done on the view itself
UIView.animate(withDuration: 0.1, animations: { [unowned self] in
self.transform = CGAffineTransform(rotationAngle: CGFloat(heading * .pi / 180.0 ))
})
}
}
and heading is forwarded from here:
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
{
if let lastLocation = locations.last {
userLocationAnnotation.coordinate = lastLocation.coordinate
}
}
I can't figure out, why my location heading is acting so weird.

Answer 1

Okay, I managed to kinda solve this.
Here is the new result: https://imgur.com/a/YJ1H683
What I did was:
func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) {
if let heading = mapView.userLocation.heading {
userLocationAnnotation.heading = -mapView.camera.heading + (heading.trueHeading > 0 ? heading.trueHeading : heading.magneticHeading)
} else {
userLocationAnnotation.heading = -mapView.camera.heading + (newHeading.trueHeading > 0 ? newHeading.trueHeading : newHeading.magneticHeading)
}
}
So - in case I am using userlocation with trackingmode == .followWithHeading, this is working great. My icon is on top of the original icon.
To hide original user icon and show yours instead - return a custom annotation view (with nothing to render) for userlocation:
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
guard !(annotation is MKUserLocation) else {
var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: "AnnotationView")
if annotationView == nil {
annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: "AnnotationView")
}
return annotationView
}
if let annotation = annotation as? Annotation {
var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: NSStringFromClass(Annotation.self))
if (annotationView == nil) {
annotationView = AnnotationView(annotation: annotation as MKAnnotation, reuseIdentifier: NSStringFromClass(Annotation.self))
} else {
annotationView!.annotation = annotation as MKAnnotation
}
annotation.headingDelegate = annotationView as? HeadingDelegate
annotationView!.image = UIImage.init(named: "user_pin")
return annotationView
}
return nil
}
Thus the result is:
1.) Get original apple maps user location + followWithHeading, but with a custom pin and correct location.
2.) I can adjust my custom location pin location to some different coordinates, but keep in mind, that followWithHeading will rotate around the real userLocation coordinates.
3.) I have also noticed, that without userlocation, the original calculation:
userLocationAnnotation.heading = -mapView.camera.heading + (newHeading.trueHeading > 0 ? newHeading.trueHeading : newHeading.magneticHeading)
Is also .. kinda okay, if I move and rotate. It is faulty, if I just rotate in place. Still cannot solve that one.
I also managed to make a custom followWithHeading, with this function:
func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) {
mapView.centerCoordinate = userLocationAnnotation.coordinate
mapView.camera.heading = (newHeading.trueHeading > 0 ? newHeading.trueHeading : newHeading.magneticHeading)
userLocationAnnotation.heading = -mapView.camera.heading + (newHeading.trueHeading > 0 ? newHeading.trueHeading : newHeading.magneticHeading)
}
But the result is not as fluid as the original apple map rotation.
If I rotate fast, then it is fine. But if I slowly turn my device, then the rotation is visibly not smooth.
See the result: https://imgur.com/a/SusV61a