我正在使用基于MKMapView的应用程序。我需要澄清是否有可能消除MKMapView中的引脚OverLap？因为在某些地方有大量的针脚显示。我很难确定销钉。
答案 0 :(得分：4)
如果您有Apple开发者帐户，我强烈建议您从名为“使用MapKit按地理位置可视化信息”的2011 WWDC Conference Sessions获取Session 111视频。其中一个细分专门介绍了如何从大型数据集中聚类内容，以便根据不同缩放级别的密度对引脚进行分组或取消组合。
他们的例子非常简单，但问题的核心是你想用一个引脚替换一组重叠的引脚，当你放大时，单个引脚会分裂回各个引脚。
您决定如何以及何时对事物进行分组可能会有很大差异。 Apple的解决方案只是将地图细分为网格，任何包含1个以上引脚的框都会产生一个组。您还可以采用算法方法，例如使用非常简单的kMeansCluster算法，您可以通过算法提供所有注释，并在逻辑上组织另一方的组数组。
从那里开始跟踪所有单个引脚以及放大和缩小时它们的分组方式。您只会为每个组或剩余的任何单个引脚显示单个注释。当地图放大和缩小时，也可以为过渡设置动画，这样您就可以在视觉上强化正在发生的事情。
我自己的技术与Apple的发布方式过于密切，因此我希望您能够访问上述几乎涵盖所有这些观点的视频。
答案 1 :(得分：1)
为此，您必须在地图中实现聚类概念。通过使用Apple演示代码，我们可以轻松地在代码中实现聚类概念。 man page
我们可以使用以下代码进行群集
实施群集的步骤
Step1：重要的是聚类我们使用两个mapview（allAnnotationsMapView），一个用于参考（allAnnotationsMapView）。
@property (nonatomic, strong) MKMapView *allAnnotationsMapView;
@property (nonatomic, strong) IBOutlet MKMapView *mapView;
在 viewDidLoad
中 _allAnnotationsMapView = [[MKMapView alloc] initWithFrame:CGRectZero];
Step2：将所有注释添加到_allAnnotationsMapView，下面_photos是注释数组。
[_allAnnotationsMapView addAnnotations:_photos];
[self updateVisibleAnnotations];
Step3：添加以下方法进行聚类，在此PhotoAnnotation中是自定义注释。 MapViewDelegate方法
- (void)mapView:(MKMapView *)aMapView regionDidChangeAnimated:(BOOL)animated {
[self updateVisibleAnnotations];
}
- (void)mapView:(MKMapView *)aMapView didAddAnnotationViews:(NSArray *)views {
for (MKAnnotationView *annotationView in views) {
if (![annotationView.annotation isKindOfClass:[PhotoAnnotation class]]) {
continue;
}
PhotoAnnotation *annotation = (PhotoAnnotation *)annotationView.annotation;
if (annotation.clusterAnnotation != nil) {
// animate the annotation from it's old container's coordinate, to its actual coordinate
CLLocationCoordinate2D actualCoordinate = annotation.coordinate;
CLLocationCoordinate2D containerCoordinate = annotation.clusterAnnotation.coordinate;
// since it's displayed on the map, it is no longer contained by another annotation,
// (We couldn't reset this in -updateVisibleAnnotations because we needed the reference to it here
// to get the containerCoordinate)
annotation.clusterAnnotation = nil;
annotation.coordinate = containerCoordinate;
[UIView animateWithDuration:0.3 animations:^{
annotation.coordinate = actualCoordinate;
}];
}
}
}
群集处理方法
- (id<MKAnnotation>)annotationInGrid:(MKMapRect)gridMapRect usingAnnotations:(NSSet *)annotations {
// first, see if one of the annotations we were already showing is in this mapRect
NSSet *visibleAnnotationsInBucket = [self.mapView annotationsInMapRect:gridMapRect];
NSSet *annotationsForGridSet = [annotations objectsPassingTest:^BOOL(id obj, BOOL *stop) {
BOOL returnValue = ([visibleAnnotationsInBucket containsObject:obj]);
if (returnValue)
{
*stop = YES;
}
return returnValue;
}];
if (annotationsForGridSet.count != 0) {
return [annotationsForGridSet anyObject];
}
// otherwise, sort the annotations based on their distance from the center of the grid square,
// then choose the one closest to the center to show
MKMapPoint centerMapPoint = MKMapPointMake(MKMapRectGetMidX(gridMapRect), MKMapRectGetMidY(gridMapRect));
NSArray *sortedAnnotations = [[annotations allObjects] sortedArrayUsingComparator:^(id obj1, id obj2) {
MKMapPoint mapPoint1 = MKMapPointForCoordinate(((id<MKAnnotation>)obj1).coordinate);
MKMapPoint mapPoint2 = MKMapPointForCoordinate(((id<MKAnnotation>)obj2).coordinate);
CLLocationDistance distance1 = MKMetersBetweenMapPoints(mapPoint1, centerMapPoint);
CLLocationDistance distance2 = MKMetersBetweenMapPoints(mapPoint2, centerMapPoint);
if (distance1 < distance2) {
return NSOrderedAscending;
} else if (distance1 > distance2) {
return NSOrderedDescending;
}
return NSOrderedSame;
}];
PhotoAnnotation *photoAnn = sortedAnnotations[0];
NSLog(@"lat long %f %f", photoAnn.coordinate.latitude, photoAnn.coordinate.longitude);
return sortedAnnotations[0];
}
- (void)updateVisibleAnnotations {
// This value to controls the number of off screen annotations are displayed.
// A bigger number means more annotations, less chance of seeing annotation views pop in but decreased performance.
// A smaller number means fewer annotations, more chance of seeing annotation views pop in but better performance.
static float marginFactor = 2.0;
// Adjust this roughly based on the dimensions of your annotations views.
// Bigger numbers more aggressively coalesce annotations (fewer annotations displayed but better performance).
// Numbers too small result in overlapping annotations views and too many annotations on screen.
static float bucketSize = 60.0;
// find all the annotations in the visible area + a wide margin to avoid popping annotation views in and out while panning the map.
MKMapRect visibleMapRect = [self.mapView visibleMapRect];
MKMapRect adjustedVisibleMapRect = MKMapRectInset(visibleMapRect, -marginFactor * visibleMapRect.size.width, -marginFactor * visibleMapRect.size.height);
// determine how wide each bucket will be, as a MKMapRect square
CLLocationCoordinate2D leftCoordinate = [self.mapView convertPoint:CGPointZero toCoordinateFromView:self.view];
CLLocationCoordinate2D rightCoordinate = [self.mapView convertPoint:CGPointMake(bucketSize, 0) toCoordinateFromView:self.view];
double gridSize = MKMapPointForCoordinate(rightCoordinate).x - MKMapPointForCoordinate(leftCoordinate).x;
MKMapRect gridMapRect = MKMapRectMake(0, 0, gridSize, gridSize);
// condense annotations, with a padding of two squares, around the visibleMapRect
double startX = floor(MKMapRectGetMinX(adjustedVisibleMapRect) / gridSize) * gridSize;
double startY = floor(MKMapRectGetMinY(adjustedVisibleMapRect) / gridSize) * gridSize;
double endX = floor(MKMapRectGetMaxX(adjustedVisibleMapRect) / gridSize) * gridSize;
double endY = floor(MKMapRectGetMaxY(adjustedVisibleMapRect) / gridSize) * gridSize;
// for each square in our grid, pick one annotation to show
gridMapRect.origin.y = startY;
while (MKMapRectGetMinY(gridMapRect) <= endY) {
gridMapRect.origin.x = startX;
while (MKMapRectGetMinX(gridMapRect) <= endX) {
NSSet *allAnnotationsInBucket = [self.allAnnotationsMapView annotationsInMapRect:gridMapRect];
NSSet *visibleAnnotationsInBucket = [self.mapView annotationsInMapRect:gridMapRect];
// we only care about PhotoAnnotations
NSMutableSet *filteredAnnotationsInBucket = [[allAnnotationsInBucket objectsPassingTest:^BOOL(id obj, BOOL *stop) {
return ([obj isKindOfClass:[PhotoAnnotation class]]);
}] mutableCopy];
if (filteredAnnotationsInBucket.count > 0) {
PhotoAnnotation *annotationForGrid = (PhotoAnnotation *)[self annotationInGrid:gridMapRect usingAnnotations:filteredAnnotationsInBucket];
[filteredAnnotationsInBucket removeObject:annotationForGrid];
// give the annotationForGrid a reference to all the annotations it will represent
annotationForGrid.containedAnnotations = [filteredAnnotationsInBucket allObjects];
[self.mapView addAnnotation:annotationForGrid];
for (PhotoAnnotation *annotation in filteredAnnotationsInBucket) {
// give all the other annotations a reference to the one which is representing them
annotation.clusterAnnotation = annotationForGrid;
annotation.containedAnnotations = nil;
// remove annotations which we've decided to cluster
if ([visibleAnnotationsInBucket containsObject:annotation]) {
CLLocationCoordinate2D actualCoordinate = annotation.coordinate;
[UIView animateWithDuration:0.3 animations:^{
annotation.coordinate = annotation.clusterAnnotation.coordinate;
} completion:^(BOOL finished) {
annotation.coordinate = actualCoordinate;
[self.mapView removeAnnotation:annotation];
}];
}
}
}
gridMapRect.origin.x += gridSize;
}
gridMapRect.origin.y += gridSize;
}
}
通过以上步骤，我们可以在mapview上实现集群，没有必要使用任何第三方代码或框架。请在此处查看Reference link。如果您对此有任何疑问，请告诉我。
答案 2 :(得分：1)
实现自己的注释聚类框架非常容易。这是一个基本示例，您可以参考here。
答案 3 :(得分：0)
如果您的引脚重叠，则必须确保该位置的缩放级别很高。 您可以考虑删除该缩放级别中的某些注释，直到您没有注释重叠，并且在放大时可以添加注释，以便注释之间有足够的空间。