在iOS地图上绘制两点间路线

当我们获取了一组地理位置后，可能会想要在地图上绘制这组地理位置信息所包含的路线。

MKMapView提供了addOverlay功能（以及addAnnotation），让我们可以在地图上放一层遮罩。如果要放一组遮罩，可以用addOverlays。

#pragma mark - - (void)drawLineWithLocationArray:(NSArray *)locationArray{    int pointCount = [locationArray count];    CLLocationCoordinate2D *coordinateArray = (CLLocationCoordinate2D *)malloc(pointCount * sizeof(CLLocationCoordinate2D));    for (int i = 0; i < pointCount; ++i) {        CLLocation *location = [locationArray objectAtIndex:i];        coordinateArray[i] = [location coordinate];    }    self.routeLine = [MKPolyline polylineWithCoordinates:coordinateArray count:pointCount];    [self.mapView setVisibleMapRect:[self.routeLine boundingMapRect]];    [self.mapView addOverlay:self.routeLine];    free(coordinateArray);    coordinateArray = NULL;}

MKPolyLine为我们提供了方便绘制多条线段的功能，它实现了MKOverlay协议，但并不能作为遮罩。我们需要实现相应的遮罩代理方法

#pragma mark - MKMapViewDelegate- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id)overlay{    if(overlay == self.routeLine) {        if(nil == self.routeLineView) {            self.routeLineView = [[[MKPolylineView alloc] initWithPolyline:self.routeLine] autorelease];            self.routeLineView.fillColor = [UIColor redColor];            self.routeLineView.strokeColor = [UIColor redColor];            self.routeLineView.lineWidth = 5;        }        return self.routeLineView;    }    return nil;}

下面是我的测试代码，用北京的经纬度和杭州的经纬度画线：

- (void)drawTestLine{    CLLocation *location0 = [[CLLocation alloc] initWithLatitude:39.954245 longitude:116.312455];    CLLocation *location1 = [[CLLocation alloc] initWithLatitude:30.247871 longitude:120.127683];    NSArray *array = [NSArray arrayWithObjects:location0, location1, nil];    [self drawLineWithLocationArray:array];}

俩目标点间连线的实现
绘制结果如下：