刷新 iPhone MapView 时出现问题

Question

大家好，我在通过 setNeedsDisplayInMapRect: 函数刷新地图视图中的叠加层时遇到问题。这是相关代码：

ParkingMapViewController.m:

for (ParkingRegionOverlay *overlay in mapView.overlays) {
    [overlay setNeedsDisplayInMapRect:self.mapView.visibleMapRect];
}

//...
- (MKOverlayView *)mapView:(MKMapView *)mapView 
            viewForOverlay:(id <MKOverlay>)overlay
{   
    NSLog(@"ParkingMapViewController.m mapView:viewForOverlay");
    //...
}
//...

ParkingRegionOverlay.h:

@interface ParkingRegionOverlay : MKOverlayView <MKOverlay> {
    MKPolygon *polygon;
    MKMapRect boundingRect;
    CLLocationCoordinate2D centerCoord;
    //...
}
//...

我没有将“ParkingMapViewController.m mapView:viewForOverlay”输出发送到我期望的控制台。我已经完成了调试器并确保到达并执行了 for 循环，但是由于某种原因没有调用 mapView:viewForOverlay: 。有人知道我做错了什么吗？提前致谢！

编辑1：

我相信我已经正确设置了委托、坐标和边界矩形，但请看一下...

ParkingMapViewController.h

@interface ParkingMapViewController : UIViewController <MKMapViewDelegate> {
    MKMapView *mapView;
//...

ParkingMapViewController.m：

//...
- (void)viewDidLoad {
    [super viewDidLoad];
    mapView.delegate = self;
//...

ParkingRegionOverlay.m：

//...
//initializes polygon and calculates bounding rect as well as its center coordinate
-(id)initWithPoints:(NSArray *)pointsArray andTitle:(NSString *)overlayTitle{
    MKMapPoint points[[pointsArray count]];
    double maxX = MIN_COORD_VAL;
    double minX = MAX_COORD_VAL;
    double maxY = MIN_COORD_VAL;
    double minY = MAX_COORD_VAL;
    double tempX = 0;
    double tempY = 0;

    if (self = [super init]) {
        int i = 0;
        //determine min/max extrema to help calculate the bounding rect
        for (id coordDict in pointsArray){
            tempX = [[coordDict objectForKey:@"latitude"] doubleValue];
            tempY = [[coordDict objectForKey:@"longitude"] doubleValue];
            maxX = fmax(tempX, maxX);
            minX = fmin(tempX, minX);
            maxY = fmax(tempY, maxY);
            minY = fmin(tempY, minY);

            CLLocationCoordinate2D coord = {tempX,tempY};
            points[i] = MKMapPointForCoordinate(coord);
            i++;
        }//for

        CLLocationCoordinate2D northWestCorner = CLLocationCoordinate2DMake(maxX, minY);
        CLLocationCoordinate2D southEastCorner = CLLocationCoordinate2DMake(minX, maxY);
        MKMapPoint northWestPoint = MKMapPointForCoordinate(northWestCorner);
        MKMapPoint southEastPoint = MKMapPointForCoordinate(southEastCorner);
        boundingRect = MKMapRectMake(northWestPoint.x, northWestPoint.y, 
                                     (southEastPoint.x-northWestPoint.x), 
                                     (southEastPoint.y-northWestPoint.y));

        centerCoord = CLLocationCoordinate2DMake((maxX-minX)/2,(maxY-minY)/2);
        polygon = [MKPolygon polygonWithPoints:points count:[pointsArray count]];
        polygon.title = overlayTitle;

        [self initAcceptedPermitsBasedOnTitle:overlayTitle];
    }//if

    return self;
}
//...

谢谢。

编辑2：

我尝试过另一种方法，但无济于事：

ParkingMapViewController.m

    NSArray *overlayArray = [[NSArray alloc] initWithArray:[mapView overlays]];
    [self.mapView removeOverlays:mapView.overlays];
    [self.mapView addOverlays:overlayArray];

删除并重新添加所有叠加层对我来说效果不太好。当执行第三行时它只会崩溃。有什么想法吗？

编辑3：

所以我将之前发布的代码更改为以下内容：

NSArray *overlayArray = [mapView overlays];
[self.mapView removeOverlays:overlayArray];
[self.mapView addOverlays:overlayArray];

现在我在控制台中看到了这一点：

2011-05-05 14:24:54.145 Parking[68501:207] -[NSCFNumber boundingMapRect]: unrecognized selector sent to instance 0xa9afae0
2011-05-05 14:24:54.147 Parking[68501:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFNumber boundingMapRect]: unrecognized selector sent to instance 0xa9afae0'

Answer 1

您可能没有正确设置 MKOverlay 上的坐标或 boundingMapRect 属性。 MapView 仅在认为视图可能可见时才会请求视图，如果其可见矩形不与 boundMapRect 相交，则不会。

另请确保您的 mapView 的 delegate 设置正确。

Answer 2

所以我想通了。不一定是最有效的方法，但它对我有用。这就是我所做的：

[self.mapView removeOverlays:[mapView overlays]];
[self loadOverlaysAndAnnotations];

这是 loadOverlaysAndAnnotations：

- (void)loadOverlaysAndAnnotations {

    NSError *error;
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    CoreDataSingleton *coreDataSingleton = [CoreDataSingleton sharedManager];
    NSEntityDescription *entity = [NSEntityDescription 
                                   entityForName:@"ParkingLot" inManagedObjectContext:[coreDataSingleton managedObjectContext]];
    [fetchRequest setEntity:entity];
    NSArray *fetchedObjects = [[coreDataSingleton managedObjectContext] executeFetchRequest:fetchRequest error:&error];
    for (NSManagedObject *overlayEntity in fetchedObjects) {
        NSArray *pointsArray = [NSArray arrayWithArray:[overlayEntity valueForKey:@"overlayCoordPoints"]];
        ParkingRegionOverlay *regionPolygon = [[ParkingRegionOverlay alloc] initWithPoints:pointsArray andTitle:[overlayEntity valueForKey:@"lotName"]];
        [mapView addOverlay:regionPolygon];
        [regionPolygon release];


        NSSet *annotationsSet = [NSSet setWithSet:[overlayEntity valueForKey:@"parkingAnnotations"]];
        NSArray *allAnnotations = [NSArray arrayWithArray:[annotationsSet allObjects]];
        CLLocationCoordinate2D workingCoordinate;
        for (ParkingAnnotations *annotation in allAnnotations) {
            ParkingAnnotation *parkingAnnot = [[ParkingAnnotation alloc] init];
            workingCoordinate.latitude = [[annotation latitude] doubleValue];
            workingCoordinate.longitude = [[annotation longitude] doubleValue];
            [parkingAnnot setCoordinate:workingCoordinate];
            [parkingAnnot setTitle:[overlayEntity valueForKey:@"lotName"]];
            if ([[overlayEntity valueForKey:@"lotName"] isEqualToString:@"VP 1"]) {
                [parkingAnnot setLot:lot1];
            }

            [mapView addAnnotation:parkingAnnot];
            [parkingAnnot release];
        }
    }        
    [fetchRequest release];
}//loadOverlaysAndAnnotations

简而言之，我不必创建新函数，而只需调用我用来将叠加层加载到地图视图中的函数，效果很好！希望这可以帮助其他陷入类似情况的人。

编辑：

请务必注意，我正在重新加载注释和叠加层，如果没有先删除注释和叠加层，则如果重新加载函数被调用太多次，可能会导致应用程序崩溃。这就是我目前正在经历的。只是需要注意一些事情。为了解决这个问题，我将拥有单独的加载函数，一个用于覆盖，一个用于注释，这将被适当地调用。