Question

我使用此代码将折线（地图上的点）与折线连接：

CLLocationCoordinate2D coordinates[allLocations.count];
    int i = 0;
    for (locHolder *location in allLocations) {
        coordinates[i] = CLLocationCoordinate2DMake([location.lat floatValue], [location floatValue]);
        i++;
    }
    MKPolyline *polyline = [MKPolyline polylineWithCoordinates:coordinates count:[allLocations count]];
    self->polyline = polyline;
    [self.mapView addOverlay:self->polyline level:MKOverlayLevelAboveRoads];

但是这段代码通过无线方式连接它们（忽略道路），是否可以将多个CLLocationCoordinate2D位置与道路之后的折线相连接？

** 还有一个问题， [allLocations count]和allLocations.count之间的性能是否有任何差异。

感谢。

Answer 1

在这些日子里，我遇到了同样的问题，并且在这里和那里寻找答案，我发现this来自Rob的答案对于这个案例非常有用。

首先，在MapViewController中，你有一个包含一个目的地的对象数组，每个对象的类型为CLLocationCoordinate2D

在MapViewController.h中

@property (nonatomic, strong) NSArray *locations;

然后，在实现中，使用如下所示的数据填充该数组：

_locations = [NSArray arrayWithObjects:
    [RouteObject routeWithOrigin:CLLocationCoordinate2DMake(-23.595571, -46.684408) destination:CLLocationCoordinate2DMake(-23.597886, -46.673950)],
    [RouteObject routeWithOrigin:CLLocationCoordinate2DMake(-23.597886, -46.673950) destination:CLLocationCoordinate2DMake(-23.597591, -46.666805)],
    [RouteObject routeWithOrigin:CLLocationCoordinate2DMake(-23.597591, -46.666805) destination:CLLocationCoordinate2DMake(-23.604061, -46.662728)], nil];

现在您已拥有原点和目的地数组，您可以开始在它们之间绘制路线（从A到B，从B到C以及从C到D）。

添加一个按钮，然后连接IBAction，这样你就可以进行魔术了。

- (IBAction)btnDirectionsPressed:(id)sender {
    [self enableUI:NO];    // This method enables or disables all the UI elements that interact with the user

    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);     // Create the semaphore    

    __block NSMutableArray *routes = [[NSMutableArray alloc] init];         // Arrays to store MKRoute objects and MKAnnotationPoint objects, so then we can draw them on the map
    __block NSMutableArray *annotations = [[NSMutableArray alloc] init];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
        for (RouteObject *routeObject in _locations) {
            MKDirectionsRequest *directionsRequest = [MKDirectionsRequest new];
            [directionsRequest setTransportType:MKDirectionsTransportTypeAutomobile];
            [directionsRequest setSource:[routeObject originMapItem]];
            [directionsRequest setDestination:[routeObject destinationMapItem]];
            [directionsRequest setRequestsAlternateRoutes:NO];

            MKDirections *direction = [[MKDirections alloc] initWithRequest:directionsRequest];

            // For each object in the locations array, we request that route from its origin and its destination
            [direction calculateDirectionsWithCompletionHandler: ^(MKDirectionsResponse *response, NSError *error) {   
                if (error) {
                    NSLog(@"There was an error getting your directions");
                    return;
                }

                MKRoute *route = [response.routes firstObject];   
                [routes addObject:route];
                [annotations addObject:[routeObject destinationAnnotation]];

                dispatch_semaphore_signal(semaphore);    // Send the signal that one semaphore is ready to consume
            }];
        }
    });

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
        for (int i = 0; i < _locations.count; i++) {
            dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);    // Wait until one semaphore is ready to consume

            dispatch_async(dispatch_get_main_queue(), ^{    // For each element, dispatch to the main queue to draw route and annotation corresponding to that location
                MKRoute *route = routes[i];
                [self.mapView addOverlay:route.polyline];
                [self.mapView addAnnotation:annotations[i]];
            });
        }

        dispatch_async(dispatch_get_main_queue(), ^{   // Finally, dispatch to the main queue enabling elements and resizing map to show all the annotations
            [self enableUI:YES];
            [self fitRegionToRoutes];
        });
    });
}

希望这有帮助！

乔尔。

iOS MapKit通过道路连接地图上的多个点

1 个答案: