How to detect taps on MKPolylines/Overlays like Maps.app?

Question

When displaying directions on the built-in Maps.app on the iPhone you can \"select\" one of the usually 3 route alternatives that are displayed by tapping on it. I wan\'t to

Answer 1

@Rashwan L : Updated his answer to Swift 4.2

let map = MKMapView()
let mapTap = UITapGestureRecognizer(target: self, action: #selector(mapTapped(_:)))
 map.addGestureRecognizer(mapTap)

 @objc private func mapTapped(_ tap: UITapGestureRecognizer) {
    if tap.state == .recognized && tap.state == .recognized {
        // Get map coordinate from touch point
        let touchPt: CGPoint = tap.location(in: skyMap)
        let coord: CLLocationCoordinate2D = skyMap.convert(touchPt, toCoordinateFrom: skyMap)
        let maxMeters: Double = meters(fromPixel: 22, at: touchPt)
        var nearestDistance: Float = MAXFLOAT
        var nearestPoly: MKPolyline? = nil
        // for every overlay ...
        for overlay: MKOverlay in skyMap.overlays {
            // .. if MKPolyline ...
            if (overlay is MKPolyline) {
                // ... get the distance ...
                let distance: Float = Float(distanceOf(pt: MKMapPoint(coord), toPoly: overlay as! MKPolyline))
                // ... and find the nearest one
                if distance < nearestDistance {
                    nearestDistance = distance
                    nearestPoly = overlay as? MKPolyline
                }

            }
        }

        if Double(nearestDistance) <= maxMeters {
            print("Touched poly: \(nearestPoly) distance: \(nearestDistance)")

        }
    }
}

private func distanceOf(pt: MKMapPoint, toPoly poly: MKPolyline) -> Double {
    var distance: Double = Double(MAXFLOAT)
    for n in 0.. 1.0 {
            ptClosest = ptB
        }
        else {
            ptClosest = MKMapPoint(x: ptA.x + u * xDelta, y: ptA.y + u * yDelta)
        }

        distance = min(distance, ptClosest.distance(to: pt))
    }
    return distance
}

private func meters(fromPixel px: Int, at pt: CGPoint) -> Double {
    let ptB = CGPoint(x: pt.x + CGFloat(px), y: pt.y)
    let coordA: CLLocationCoordinate2D = skyMap.convert(pt, toCoordinateFrom: skyMap)
    let coordB: CLLocationCoordinate2D = skyMap.convert(ptB, toCoordinateFrom: skyMap)
    return MKMapPoint(coordA).distance(to: MKMapPoint(coordB))
}