我想在 map 上的两个位置之间绘制一条路线。有点像导游。当游客点击另一个位置时，我希望能够绘制一条路线；以及，告知与当前位置的距离。

我知道 Internet 上的一些网站告诉我们如何在 map 上绘制多段线。但是，大多数示例都有一个带有各种坐标的预加载 .csv 文件。

是否有其他方法可以从 Google 或任何其他提供商获取坐标，因为位置是动态选择的。

如果不是，我如何获取中间坐标的信息？

iOS 6 是否提供了解决此问题的任何直接方法？

最佳答案

以下 viewDidLoad 将 (1) 设置两个位置，(2) 删除所有先前的注释，以及 (3) 调用用户定义的辅助函数(获取路线点并绘制路线)。

-(void)viewDidLoad
{
    [super viewDidLoad];

    // Origin Location.
    CLLocationCoordinate2D loc1;
    loc1.latitude = 29.0167;
    loc1.longitude = 77.3833;
    Annotation *origin = [[Annotation alloc] initWithTitle:@"loc1" subTitle:@"Home1" andCoordinate:loc1];
    [objMapView addAnnotation:origin];

    // Destination Location.
    CLLocationCoordinate2D loc2;
    loc2.latitude = 19.076000;
    loc2.longitude = 72.877670;
    Annotation *destination = [[Annotation alloc] initWithTitle:@"loc2" subTitle:@"Home2" andCoordinate:loc2];
    [objMapView addAnnotation:destination];

    if(arrRoutePoints) // Remove all annotations
        [objMapView removeAnnotations:[objMapView annotations]];

    arrRoutePoints = [self getRoutePointFrom:origin to:destination];
    [self drawRoute];
    [self centerMap];
}

下面是MKMapViewDelegate方法，绘制叠加层(iOS 4.0及以后版本)。

/* MKMapViewDelegate Meth0d -- for viewForOverlay*/
- (MKOverlayView*)mapView:(MKMapView*)theMapView viewForOverlay:(id <MKOverlay>)overlay
{
    MKPolylineView *view = [[MKPolylineView alloc] initWithPolyline:objPolyline];
    view.fillColor = [UIColor blackColor];
    view.strokeColor = [UIColor blackColor];
    view.lineWidth = 4;
    return view;
}

以下函数将同时获取位置和准备 URL 以获取所有路线点。当然，还会调用 stringWithURL。

/* This will get the route coordinates from the Google API. */
- (NSArray*)getRoutePointFrom:(Annotation *)origin to:(Annotation *)destination
{
    NSString* saddr = [NSString stringWithFormat:@"%f,%f", origin.coordinate.latitude, origin.coordinate.longitude];
    NSString* daddr = [NSString stringWithFormat:@"%f,%f", destination.coordinate.latitude, destination.coordinate.longitude];

    NSString* apiUrlStr = [NSString stringWithFormat:@"http://maps.google.com/maps?output=dragdir&saddr=%@&daddr=%@", saddr, daddr];
    NSURL* apiUrl = [NSURL URLWithString:apiUrlStr];

    NSError *error;
    NSString *apiResponse = [NSString stringWithContentsOfURL:apiUrl encoding:NSUTF8StringEncoding error:&error];
    NSString* encodedPoints = [apiResponse stringByMatching:@"points:\\\"([^\\\"]*)\\\"" capture:1L];

    return [self decodePolyLine:[encodedPoints mutableCopy]];
}

以下代码是真正的魔法(我们从 API 获得的响应的解码器)。除非我知道自己在做什么，否则我不会修改该代码:)

- (NSMutableArray *)decodePolyLine:(NSMutableString *)encodedString
{
    [encodedString replaceOccurrencesOfString:@"\\\\" withString:@"\\"
                                  options:NSLiteralSearch
                                    range:NSMakeRange(0, [encodedString length])];
    NSInteger len = [encodedString length];
    NSInteger index = 0;
    NSMutableArray *array = [[NSMutableArray alloc] init];
    NSInteger lat=0;
    NSInteger lng=0;
    while (index < len) {
        NSInteger b;
        NSInteger shift = 0;
        NSInteger result = 0;
        do {
            b = [encodedString characterAtIndex:index++] - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        NSInteger dlat = ((result & 1) ? ~(result >> 1) : (result >> 1));
        lat += dlat;
        shift = 0;
        result = 0;
        do {
            b = [encodedString characterAtIndex:index++] - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
       } while (b >= 0x20);
        NSInteger dlng = ((result & 1) ? ~(result >> 1) : (result >> 1));
        lng += dlng;
        NSNumber *latitude = [[NSNumber alloc] initWithFloat:lat * 1e-5];
        NSNumber *longitude = [[NSNumber alloc] initWithFloat:lng * 1e-5];
        printf("\n[%f,", [latitude doubleValue]);
        printf("%f]", [longitude doubleValue]);
        CLLocation *loc = [[CLLocation alloc] initWithLatitude:[latitude floatValue] longitude:[longitude floatValue]];
        [array addObject:loc];
    }
    return array;
}

此函数将绘制路线并添加叠加层。

- (void)drawRoute
{
    int numPoints = [arrRoutePoints count];
    if (numPoints > 1)
    {
        CLLocationCoordinate2D* coords = malloc(numPoints * sizeof(CLLocationCoordinate2D));
        for (int i = 0; i < numPoints; i++)
        {
            CLLocation* current = [arrRoutePoints objectAtIndex:i];
            coords[i] = current.coordinate;
        }

        self.objPolyline = [MKPolyline polylineWithCoordinates:coords count:numPoints];
        free(coords);

        [objMapView addOverlay:objPolyline];
        [objMapView setNeedsDisplay];
    }
}

以下代码将使 map 居中对齐。

- (void)centerMap
{
    MKCoordinateRegion region;

    CLLocationDegrees maxLat = -90;
    CLLocationDegrees maxLon = -180;
    CLLocationDegrees minLat = 90;
    CLLocationDegrees minLon = 180;

    for(int idx = 0; idx < arrRoutePoints.count; idx++)
    {
        CLLocation* currentLocation = [arrRoutePoints objectAtIndex:idx];

        if(currentLocation.coordinate.latitude > maxLat)
            maxLat = currentLocation.coordinate.latitude;
        if(currentLocation.coordinate.latitude < minLat)
            minLat = currentLocation.coordinate.latitude;
        if(currentLocation.coordinate.longitude > maxLon)
            maxLon = currentLocation.coordinate.longitude;
        if(currentLocation.coordinate.longitude < minLon)
            minLon = currentLocation.coordinate.longitude;
    }

    region.center.latitude     = (maxLat + minLat) / 2;
    region.center.longitude    = (maxLon + minLon) / 2;
    region.span.latitudeDelta  = maxLat - minLat;
    region.span.longitudeDelta = maxLon - minLon;

    [objMapView setRegion:region animated:YES];
}

我希望这会对某人有所帮助。

关于ios - 在 iOS 的 MapKit 中绘制路线，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/2834523/