使用Swift绘制折线 [英] Draw polyline using Swift

问题描述

我试图了解如何使用Swift绘制折线。我查看了文档，引用了一些教程，并查看了其他一些SO帖子，但我仍然无法在地图上画一条线。这是我的代码。有谁告诉我这里我做错了什么？

I'm trying to get an understanding of how to draw polylines using Swift. I've looked at the documentation, referenced some tutorials, and checked out some other SO posts, but I still can't get the thing to draw a line on my map. Here's my code. Anyone tell me what I'm doing wrong here?

import UIKit
import MapKit

class FirstViewController: UIViewController {

    @IBOutlet weak var map: MKMapView!

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)

        let location = CLLocationCoordinate2D(
            latitude: -73.761105,
            longitude: 41.017791
        )

        let span = MKCoordinateSpanMake(0.07, 0.07)
        let region = MKCoordinateRegion(center: location, span: span)
        map.setRegion(region, animated: true)

        let annotation = MKPointAnnotation()
        annotation.setCoordinate(location)
        annotation.title = "White Plains"
        annotation.subtitle = "Westchester County"
        map.addAnnotation(annotation)

        var locations = [CLLocation(latitude: -73.761105, longitude: 41.017791), CLLocation(latitude: -73.760701,longitude: 41.019348), CLLocation(latitude: -73.757201, longitude: 41.019267), CLLocation(latitude: -73.757482, longitude: 41.016375), CLLocation(latitude: -73.761105, longitude: 41.017791)]
        var coordinates = locations.map({(location: CLLocation!) -> CLLocationCoordinate2D in return location.coordinate})
        var polyline = MKPolyline(coordinates: &coordinates, count: locations.count)

        self.map.addOverlay(polyline)

    }

    func mapView(mapView: MKMapView!, rendererForOverlay overlay: MKOverlay!) -> MKOverlayRenderer! {
        if overlay is MKPolyline {
            var polylineRenderer = MKPolylineRenderer(overlay: overlay)
            polylineRenderer.strokeColor = UIColor.blueColor()
            polylineRenderer.lineWidth = 5
            return polylineRenderer
        }

        return nil
    }

}

谢谢！

推荐答案

这里 MKGeodesicPolyline 将解决您的问题。添加 MKGeodesicPolyline 的对象，而不是 MKPolyline 。

Here MKGeodesicPolyline will solve your problem. Add object of MKGeodesicPolyline instead of MKPolyline.

In你的代码删除两行以下：

In your code remove below two lines:

    let polyline = MKPolyline(coordinates: &coordinates, count: locations.count)
    map.add(polyline)

并添加以下行：

    let geodesic = MKGeodesicPolyline(coordinates: coordinates, count: 2)
    map.add(geodesic)

Swift代码：

func createPolyline(mapView: MKMapView) {
    let point1 = CLLocationCoordinate2DMake(-73.761105, 41.017791);
    let point2 = CLLocationCoordinate2DMake(-73.760701, 41.019348);
    let point3 = CLLocationCoordinate2DMake(-73.757201, 41.019267);
    let point4 = CLLocationCoordinate2DMake(-73.757482, 41.016375);
    let point5 = CLLocationCoordinate2DMake(-73.761105, 41.017791);

    let points: [CLLocationCoordinate2D]
    points = [point1, point2, point3, point4, point5]

    let geodesic = MKGeodesicPolyline(coordinates: points, count: 5)
    map.add(geodesic)

    UIView.animate(withDuration: 1.5, animations: { () -> Void in
        let span = MKCoordinateSpanMake(0.01, 0.01)
        let region1 = MKCoordinateRegion(center: point1, span: span)
        self.map.setRegion(region1, animated: true)
    })
}

目标C代码：

- (void) createGeoPolyline {

    CLLocationCoordinate2D point1 = { -73.761105, 41.017791 };
    CLLocationCoordinate2D point2 = { -73.760701, 41.019348 };
    CLLocationCoordinate2D point3 = { -73.757201, 41.019267 };
    CLLocationCoordinate2D point4 = { -73.757482, 41.016375 };
    CLLocationCoordinate2D point5 = { -73.761105, 41.017791 };

   CLLocationCoordinate2D points[] = {point1, point2, point3, point4, point5};

    MKGeodesicPolyline *geodesic = [MKGeodesicPolyline polylineWithCoordinates:&points[0] count:5];
    [self.mapView addOverlay:geodesic];

    [UIView animateWithDuration:1.5 animations:^{
        MKCoordinateRegion region;
        region.center = point1;

        MKCoordinateSpan span;
        span.latitudeDelta  = 0.01;
        span.longitudeDelta = 0.01;
        region.span = span;
        [self.mapView setRegion:region animated:YES];
    }];
}

以上目标C代码完美无缺，它将在下面显示叠加：

Above Objective C code works perfect and it will show overlay below:

但是如果你尝试使用Swift代码，它就不会。我尽可能多地尝试解决它，但它不会改变。可能是MapKit框架的bug。

But if you try Swift code it will not. I tried as much as I can to solve it out but It won't change. May be it is bug from MapKit framework.

这篇关于使用Swift绘制折线的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！