自定义MKOverlayView/未修改的MKPolygonView被裁剪为某些缩放级别

当在地图上添加了多个叠加层时，自定义MKOverlayView和标准MKPolygonView都被裁剪为某些缩放级别时，我遇到了问题.

I'm having an issue with both a custom MKOverlayView and standard MKPolygonView being clipped at certain zoom levels when there are multiple overlays added to a map.

两个两次缩放级别的阿尔及利亚覆盖.

三个双击缩放级别的阿尔及利亚覆盖图.注意剪辑.

一些观察结果:

• 无论我是否使用自定义MKOverlayView或返回具有相同多边形的MKPolygonView，都会发生这种情况.
• 如果我仅绘制一个叠加层，则不会发生此问题.
• 并非所有的叠加层都发生这种情况-只有一些.

就代码而言:将叠加层添加到NSMutableArray(borderOverlays)中，然后可以在其他位置访问该叠加层以加载特定国家/地区ID的叠加层. minX/minY/maxX/maxY是纬度/经度值；多边形是从ESRI shapefile构造的路径.

As far as code goes: this adds the overlay to an NSMutableArray (borderOverlays), which is then accessed elsewhere to load the overlay for a specific country ID. minX/minY/maxX/maxY are latitude/longitude values; polygon is a path constructed from an ESRI shapefile.

CLLocationCoordinate2D mbrMin = CLLocationCoordinate2DMake(minY, minX);
CLLocationCoordinate2D mbrMax = CLLocationCoordinate2DMake(maxY, maxX);
MKMapPoint minPoint = MKMapPointForCoordinate(mbrMin);
MKMapPoint maxPoint = MKMapPointForCoordinate(mbrMax);
MKMapSize size = MKMapSizeMake(maxPoint.x - minPoint.x, maxPoint.y - minPoint.y);
MKMapRect rect = MKMapRectMake(minPoint.x, minPoint.y, size.width, size.height);

if ( spans180 ) {
    rect = MKMapRectMake(minPoint.x, minPoint.y, MKMapSizeWorld.width * 2, size.height);
}

CustomMKOverlay* overlay = [[CustomMKOverlay alloc] initWithPolygon:polygon withBoundingMapRect:rect];
[borderOverlays addObject:overlay];

叠加层通过以下方式添加到地图中:

The overlay is added to the map via:

[mapView addOverlay:overlay];

viewForOverlay:

viewForOverlay:

- (MKOverlayView *)mapView:(MKMapView*)aMapView viewForOverlay:(id<MKOverlay>)overlay
{
    if ( [overlay isKindOfClass:[CustomMKOverlay class]] ) {
        /* Note: the behaviour if this chunk is not commented is the exact same as below. 
        CustomMKOverlayView* overlayView = [[[CustomMKOverlayView alloc] initWithOverlay:overlay withMapView:aMapView] autorelease];
        [borderViews addObject:overlayView];
        return overlayView; */

        MKPolygonView* view = [[[MKPolygonView alloc] initWithPolygon:((CustomMKOverlay*)overlay).polygon] autorelease];
        view.fillColor = [((CustomMKOverlay*)overlay).colour colorWithAlphaComponent:0.5f];
        view.lineWidth = 5.0f;
        view.strokeColor = [UIColor blackColor];
        [borderViews addObject:view];
        return view;
    }
}

使用MKPolygonView时，没有绘图代码(显示的示例).不过，为了完成起见，这是我的自定义绘图代码，并且会发生相同的问题.轮廓通常绘制-这实际上是调试图，它在覆盖层的boundingMapRect周围绘制一个rect，并填充它而不会与轮廓混为一谈.

When MKPolygonView is used, there is no drawing code (the example shown). For completion's sake, though, here's my custom drawing code, and the same issue occurs. The outlines normally draw - this is actually debugging drawing, which draws a rect around the boundingMapRect of the overlay and fills it without mucking around with the outlines.

- (void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CGContextRef)context
{    
    CustomMKOverlay* overlay = (CustomMKOverlay*)self.overlay;

    CGRect clipRect = [self rectForMapRect:overlay.boundingMapRect];
    CGContextAddRect(context, clipRect);
    CGContextClip(context);

    UIColor* colour = [UIColor redColor];
    colour = [colour colorWithAlphaComponent:0.5f];
    CGContextSetFillColorWithColor(context, [colour CGColor]);
    CGRect fillRect = [self rectForMapRect:overlay.boundingMapRect];
    CGContextFillRect(context, fillRect);
}

可以说，这一点我有些困惑-好像加载的缩放图块覆盖了叠加层.我已经介绍了有关TileMap和HazardMap的各种示例，但是由于我没有加载自己的地图图块，因此它们并不是很有帮助.

Suffice to say, I'm a bit stumped at this point - it's almost as if the zoomed tiled that's being loaded draws over the overlay. I've poured over various examples regarding TileMap and HazardMap, but as I am not loading my own map tiles, they're not very helpful.

我可能缺少明显的东西.任何帮助，将不胜感激.如有必要，我很乐意提供更多代码/上下文.

I'm probably missing something painfully obvious. Any help would be appreciated. I'm happy to provide more code/context if necessary.