我在理解如何向MKMapView添加多个叠加层时遇到一些麻烦。
我有跟踪的阵列路线。跟踪的路由是CLLocations数组。所以我有一个数组数组。
我可以采取一条路线并在地图视图上绘制它。但是，我需要将所有路径绘制到地图视图中。
以下是我如何为1条路线创建MKPolyline：
-(void) loadRoute
{
//So we grab an array that holds all the locations of one route.
NSArray *locations = [[NSArray alloc] initWithArray:[routesArray objectAtIndex:0]];
// while we create the route points, we will also be calculating the bounding box of our route
// so we can easily zoom in on it.
MKMapPoint northEastPoint;
MKMapPoint southWestPoint;
// create a c array of points.
MKMapPoint* pointArr = malloc(sizeof(CLLocationCoordinate2D) *[locations count]);
for(int idx = 0; idx < [locations count]; idx++)
{
CLLocation *tempLoc = (CLLocation*)[locations objectAtIndex:idx];
CLLocationDegrees latitude = tempLoc.coordinate.latitude;
CLLocationDegrees longitude = tempLoc.coordinate.longitude;
// create our coordinate and add it to the correct spot in the array
CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(latitude, longitude);
MKMapPoint point = MKMapPointForCoordinate(coordinate);
// if it is the first point, just use them, since we have nothing to compare to yet.
if (idx == 0) {
northEastPoint = point;
southWestPoint = point;
}
else
{
if (point.x > northEastPoint.x)
northEastPoint.x = point.x;
if(point.y > northEastPoint.y)
northEastPoint.y = point.y;
if (point.x < southWestPoint.x)
southWestPoint.x = point.x;
if (point.y < southWestPoint.y)
southWestPoint.y = point.y;
}
pointArr[idx] = point;
}
self.routeLine = [MKPolyline polylineWithPoints:pointArr count:[locations count]];
//Zoom in to fit route on screen
_routeRect = MKMapRectMake(southWestPoint.x, southWestPoint.y, northEastPoint.x - southWestPoint.x, northEastPoint.y - southWestPoint.y);
// clear the memory allocated earlier for the points
free(pointArr);
}
这是返回叠加层的MapKit委托调用：
#pragma mark MKMapViewDelegate
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{
MKOverlayView* overlayView = nil;
if(overlay == self.routeLine)
{
//if we have not yet created an overlay view for this overlay, create it now.
if(nil == self.routeLineView)
{
self.routeLineView = [[MKPolylineView alloc] initWithPolyline:self.routeLine];
self.routeLineView.fillColor = [UIColor redColor];
self.routeLineView.strokeColor = [UIColor redColor];
self.routeLineView.lineWidth = 3;
}
overlayView = self.routeLineView;
}
return overlayView;
}
所以上面给出的所有代码都可以正常工作。我无法弄清楚如何加载更多叠加来显示其他路线。
我认为可能在loadRoute方法中，遍历所有路由并为每个路由创建MKOverlayView。将所有MKOverlayView存储在一个数组中然后执行： [self.mapView addOverlays：array];
但它不起作用。问题是在委托方法中我不知何故需要知道返回哪个叠加层。
所以如果我可以按照以下方式做点什么：
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{
int tag = overlay.tag;
return (MKOverlayView*)[arrayOfViews objectAtIndex:tag];
}
它会正常工作。但不幸的是，它并不像那样：（
非常感谢任何帮助！
编辑：
我在ViewDidLoad中使用它来添加叠加层：
[self loadRoute];
// add the overlay to the map
if (nil != self.routeLine) {
[self.mapView addOverlay:self.routeLine];
}
// zoom in on the route.
[self zoomInOnRoute];
这是标题：
// the data representing the route points.
MKPolyline* _routeLine;
// the view we create for the line on the map
MKPolylineView* _routeLineView;
// the rect that bounds the loaded points
MKMapRect _routeRect;
答案 0 :(得分：4)
routeLine和routeLineView变量一次只能指向一个叠加层和叠加层视图，因此理论上您需要一组此类变量。
但是，根据显示的代码，您不需要首先保留对这些代码的引用。
我建议删除routeLine和routeLineView变量。
然后，您只需在本地创建一个叠加层对象，然后在viewForOverlay中返回所请求的overlay参数的视图。
在loadRoute方法中，您可以遍历routesArray，并为每条路线创建一个本地覆盖对象，并在其上调用addOverlay。
还有一种更简单的方法来构建一个界定所有路线的地图矩形，以便您可以设置地图的区域以显示所有路线。
示例：
-(void) loadRoute
{
_routeRect = MKMapRectNull;
for (int raIndex = 0; raIndex < routesArray.count; raIndex++)
{
//So we grab an array that holds all the locations of one route.
NSArray *locations = [[NSArray alloc] initWithArray:
[routesArray objectAtIndex:raIndex]];
//note we are getting object at raIndex (not 0) above
//...no change to existing code here...
//self.routeLine = [MKPolyline polylineWithPoints:pointArr count:[locations count]];
//replace above line with this...
MKPolyline *pl = [MKPolyline polylineWithPoints:pointArr count:[locations count]];
[mapView addOverlay:pl];
//Zoom in to fit route on screen
//_routeRect = MKMapRectMake(southWestPoint.x, southWestPoint.y, northEastPoint.x - southWestPoint.x, northEastPoint.y - southWestPoint.y);
//replace above line with this to create a rect around ALL routes...
if (MKMapRectIsNull(_routeRect))
_routeRect = pl.boundingMapRect;
else
_routeRect = MKMapRectUnion(_routeRect, pl.boundingMapRect);
// clear the memory allocated earlier for the points
free(pointArr);
}
}
在viewDidLoad，只需致电loadRoute，不要致电addOverlay。
viewForOverlay方法变得更加简单：
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{
MKPolylineView *pv = [[MKPolylineView alloc] initWithPolyline:overlay];
pv.fillColor = [UIColor redColor];
pv.strokeColor = [UIColor redColor];
pv.lineWidth = 3;
return pv;
}
顺便说一句，在loadRoute中，这一行：
MKMapPoint* pointArr = malloc(sizeof(CLLocationCoordinate2D) *[locations count]);
应该是：
MKMapPoint* pointArr = malloc(sizeof(MKMapPoint) *[locations count]);
它应使用MKMapPoint（不是CLLocationCoordinate2D）的大小。
它们不是一回事（即使结构碰巧是相同的字节大小）。