MKPolygon - How to determine if a CLLocationCoordinate2D is in a CLLocationCoordinate2D polygon?

Question

I have the swift code below that draws a polygon and drops an annotation on MKMapView. I am trying to figure out how i could identify if the annotation\'s coordinate is with

Answer 1

I created a Swift version of the answer by @StefanS and made it easier to read by porting the code from this answer

    func isPoint(point: MKMapPoint, insidePolygon poly: MKPolygon) -> Bool {

        let polygonVerticies = poly.points()
        var isInsidePolygon = false

        for i in 0.. point.y) || (yp1 <= point.y) && (yp0 > point.y))
            {
                // If so, get the point where it crosses that line. This is a simple solution
                // to a linear equation. Note that we can't get a division by zero here -
                // if yp1 == yp0 then the above if be false.
                let cross = (xp1 - xp0) * (point.y - yp0) / (yp1 - yp0) + xp0

                // Finally check if it crosses to the left of our test point. You could equally
                // do right and it should give the same result.
                if cross < point.x {
                    isInsidePolygon = !isInsidePolygon
                }
            }
        }

        return isInsidePolygon
    }