ios - 如何删除 map 路线的这条折线？

Question

大家好，我想做的是创建一个触发 findRandomPlace() 函数的按钮。它应该向我展示 places 数组中的一个随机位置。当它给我一个随机位置时，它应该绘制从源到目的地的折线(它确实如此)，然后如果我不喜欢那个地方，我可以再次单击按钮，它应该会显示另一个地方(它确实如此) ，问题是最后一个地方的折线。我不知道如何删除它。

let route = response.routes[0]
self.Map.add(route.polyline, level: .aboveRoads)

上面的代码是绘制折线的代码，但我不确定如何删除它。如果您能提出任何想法，请提前致谢。

var previousIndex:Int = 999999
func findRandomPlace() {//need an if statement to check if its near u or in the area
    let randomIndex = Int(arc4random_uniform(UInt32(places.count)))

    if randomIndex != previousIndex {//Makes sure next place can't be current place
        previousIndex = randomIndex

        Name.text = (places[randomIndex][0])
        Description.text = (places[randomIndex][1])


        //Draw Direction Line
        let positionX:Double? = Double(places[randomIndex][2])
        let positionY:Double? = Double(places[randomIndex][3])

        let sourceCoordinates = manager.location?.coordinate
        let destinationCoordinates = CLLocationCoordinate2DMake(positionX!, positionY!)
        print(sourceCoordinates!)

        let sourcePlacemark = MKPlacemark(coordinate: sourceCoordinates!)
        let destinationPlacemark = MKPlacemark(coordinate: destinationCoordinates)

        let sourceItem = MKMapItem(placemark: sourcePlacemark)
        let destinationItem = MKMapItem(placemark: destinationPlacemark)

        let directionRequest = MKDirectionsRequest()
        directionRequest.source = sourceItem
        directionRequest.destination = destinationItem
        directionRequest.transportType = .walking

        let directions = MKDirections(request: directionRequest)
        directions.calculate(completionHandler: {
            response, error in
            //Draw Polyline and Zoom Into It
            guard let response = response else {
                if let error = error {
                    print("error")
                }
                return
            }
            let route = response.routes[0]
            self.Map.add(route.polyline, level: .aboveRoads)
            let rect = route.polyline.boundingMapRect
            self.Map.setRegion(MKCoordinateRegionForMapRect(rect), animated: true)
        })
        } else {

            findRandomPlace()
        }

}

Answer 1

我自己想通了。我很惭愧花了这么长时间，但我很高兴我最终找到了答案。

self.Map.removeOverlays(self.Map.overlays)