如何获得MKPolyline上的等距位置? [英] How can can I get equidistant location on a MKPolyline?

问题描述

我需要在MKPolyline上找到等距的位置以添加注释，如下所示.

I need to find equidistant locations on a MKPolyline to add annotations as shown below.

下面给出了我在MKPolyline上获取位置的函数，我具有Polyline的开始和结束坐标值.但是位置略有变化，如下图所示

My function to get locations on MKPolyline is given below, I have the values start and end coordinates of Polyline. But the locations are slightly ,moving out of polyline as shown in the image below

我找到位置的功能是

func getEquidistantPoints(from startPoint: CLLocationCoordinate2D, to endPoint: CLLocationCoordinate2D, numberOfPoints: Int) -> [CLLocationCoordinate2D] {

        var midPoints: [CLLocationCoordinate2D] = []
        var newPoint: CLLocationCoordinate2D = CLLocationCoordinate2DMake(0, 0)

        let count = numberOfPoints + 1
        let latitudeModifier = (endPoint.latitude - startPoint.latitude) / Double(count)
        let longitudeModifier = (endPoint.longitude - startPoint.longitude) / Double(count)

        for i in 0..<count {
            newPoint.latitude = CLLocationDegrees(startPoint.latitude + (latitudeModifier * Double(i)))
            newPoint.longitude = CLLocationDegrees(startPoint.longitude + (longitudeModifier * Double(i)))
            midPoints.append(newPoint)
        }
        return midPoints
    }

在viewdidload

In viewdidload

let coordinatesArray = getEquidistantPoints(from: sourceCoordinate, to: destinationCoordinate, numberOfPoints: 5)

        for coordinate in coordinatesArray {
            let annotation = MKPointAnnotation()
            annotation.coordinate = coordinate
            self.mapView.addAnnotation(annotation)
        }

在计算位置时如何解决此错误?

How can I solve this error in calculating locations?

推荐答案

问题是地球是圆形的.因此，您的行"不是行；它是在标称球体表面上绘制的曲线.您不能使用简单的方法在直线上找到等距"点.您需要使用比您使用的更为严格的数学.这将证明是微不足道的.

The problem is that the earth is round. So your "line" is not a line; it is a curve traced out on the surface of a nominal sphere. You cannot find "equidistant" points along the line using your simple-minded method. You need to use some much more serious math than you are using. This will prove to be far from trivial.

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