A DraggableAnnotationView in MapBox

DraggableAnnotationView.swift

class DraggableAnnotationView: MGLAnnotationView {
    
    var didSetNewCoord: (CLLocationCoordinate2D) -> Void = { _ in }
    
    init(reuseIdentifier: String, size: CGFloat, didSetCoord: @escaping(CLLocationCoordinate2D) -> Void) {
        self.didSetNewCoord  = didSetCoord
        super.init(reuseIdentifier: reuseIdentifier)
        
        // `isDraggable` is a property of MGLAnnotationView, disabled by default.
        isDraggable = true
        // This property prevents the annotation from changing size when the map is tilted.
        scalesWithViewingDistance = false
        
        // Begin setting up the view.
        frame = CGRect(x: 0, y: 0, width: size, height: size)
        
        // If UIKit Preference
        configurePin(size: size)
        
        // If SwiftUI Preference
        let controller = UIHostingController(rootView: LocationPinView())
        controller.view.frame = frame
        controller.view.backgroundColor = .clear
        addSubview(controller.view)

        layer.opacity = 0.8

        
    }
    
    
    private func configurePin(size: CGFloat) {
        backgroundColor = UIColor(custom: .murugoBlue).withAlphaComponent(0.35)
        
//        Use CALayer’s corner radius to turn this view into a circle.
        layer.cornerRadius = size / 2
        layer.borderWidth = 50
        layer.borderColor = UIColor(custom: .murugoBlue).withAlphaComponent(0.15).cgColor
        layer.shadowColor = UIColor.black.cgColor
        layer.shadowOpacity = 0.1
        
        let imgView = UIImageView(image: UIImage(named: "pinpoint")!)
        imgView.frame.size = CGSize(width: 40, height: 60)
        imgView.center = center
        imgView.center.y = imgView.center.y - 15
        imgView.contentMode = .scaleAspectFit
        addSubview(imgView)
        
    }
    
    // These two initializers are forced upon us by Swift.
    override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    // Custom handler for changes in the annotation’s drag state.
    override func setDragState(_ dragState: MGLAnnotationViewDragState, animated: Bool) {
        super.setDragState(dragState, animated: animated)
        
        switch dragState {
        case .starting:
            print("Starting", terminator: "")
            startDragging()
        case .dragging:
            print(".", terminator: "")
        case .ending, .canceling:
            print("Ending")
            endDragging()
        case .none:
            break
        @unknown default:
            fatalError("Unknown drag state")
        }
    }
    
    // When the user interacts with an annotation, animate opacity and scale changes.
    func startDragging() {
        UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0, options: [], animations: {
            self.layer.opacity = 0.65
            self.transform = CGAffineTransform.identity.scaledBy(x: 1.2, y: 1.2)
        }, completion: nil)
        
        // Initialize haptic feedback generator and give the user a light thud.
        let hapticFeedback = UIImpactFeedbackGenerator(style: .light)
        hapticFeedback.impactOccurred()
    }
    
    func endDragging() {
        transform = CGAffineTransform.identity.scaledBy(x: 1.5, y: 1.5)
        UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0, options: [], animations: {
            self.layer.opacity = 0.8
            self.transform = CGAffineTransform.identity.scaledBy(x: 1, y: 1)
        }, completion: {_ in
            guard let annot = self.annotation else {
                return
            }
            
            self.didSetNewCoord(annot.coordinate)
        })
        
        // Give the user more haptic feedback when they drop the annotation.
        let hapticFeedback = UIImpactFeedbackGenerator(style: .light)
        hapticFeedback.impactOccurred()
    }
}