我有一个方法可以接收要在地图视图上显示的注释（自定义 PostLocationAnnotation 类），并且将它们靠近在一起，输出 PostLocationAnnotations 和 LocationGroupAnnotations 的 MKAnnotation 数组（每个集群都包含一些 PostLocationAnnotations）。这是我调用该函数的方式（在“updateAnnotations”方法中，当地图的视口发生变化时调用）：
[annotationsToAdd addObjectsFromArray:[ffMapView annotations]];
[ffMapView addAnnotations:[self clusterAnnotations:annotationsToAdd WithEpsilon:20.0f andMinPts:4]];
annotationsToAdd 最初由从服务器检索但尚未添加到地图的注释填充。因此，我将应放在地图上的注释的完整列表传递给 clusterAnnotations 方法。这是方法的主体：
- (NSArray *)clusterAnnotations:(NSArray *)annotations WithEpsilon:(float)eps andMinPts:(int)minPts
{
NSMutableSet *D = [[NSMutableSet alloc] initWithCapacity:[annotations count]];
NSMutableArray *C = [[NSMutableArray alloc] init];
for (id <MKAnnotation> annotation in annotations)
{
if ([annotation isKindOfClass:[PostLocationAnnotation class]])
{
NSMutableDictionary *dictEntry = [NSMutableDictionary dictionaryWithObjectsAndKeys:
annotation, @"point",
[NSNumber numberWithBool:NO], @"visited",
[NSNumber numberWithBool:NO], @"noise",
[NSNumber numberWithBool:NO], @"clustered", nil];
[D addObject:dictEntry];
[dictEntry release];
} else if ([annotation isKindOfClass:[LocationGroupAnnotation class]])
{
for (PostLocationAnnotation *location in [(LocationGroupAnnotation *)annotation locations])
{
NSMutableDictionary *dictEntry = [NSMutableDictionary dictionaryWithObjectsAndKeys:
location, @"point",
[NSNumber numberWithBool:NO], @"visited",
[NSNumber numberWithBool:NO], @"noise",
[NSNumber numberWithBool:NO], @"clustered", nil];
[D addObject:dictEntry];
[dictEntry release];
}
}
}
for (NSMutableDictionary *P in D)
{
if ([P objectForKey:@"visited"] == [NSNumber numberWithBool:NO])
{
[P setValue:[NSNumber numberWithBool:YES] forKey:@"visited"];
NSMutableSet *N = [[NSMutableSet alloc] initWithSet:[self regionQueryForPoint:P andEpsilon:eps fromList:D]];
if ([N count] < minPts)
{
[P setValue:[NSNumber numberWithBool:YES] forKey:@"noise"];
} else {
LocationGroupAnnotation *newCluster = [[LocationGroupAnnotation alloc] initWithLocations:nil];
[C addObject:newCluster];
[self expandDbscanClusterWithPoint:P andRegion:N andCluster:newCluster andEpsilon:eps andMinPts:minPts fromList:D];
[newCluster release];
}
[N release];
}
}
NSMutableArray *annotationsToAdd = [[[NSMutableArray alloc] initWithCapacity:[annotations count]] autorelease];
for (NSMutableDictionary *P in D)
{
if ([P objectForKey:@"clustered"] == [NSNumber numberWithBool:NO])
{
[annotationsToAdd addObject:[P objectForKey:@"point"]];
}
}
for (LocationGroupAnnotation *cluster in C)
{
[cluster updateCenterCoordinate];
}
[annotationsToAdd addObjectsFromArray:(NSArray *)C];
[D release];
[C release];
return (NSArray *)annotationsToAdd;
}
当我运行它时，我收到一条僵尸消息，我发现删除 [D release] 修复了僵尸但会导致泄漏。查看 Instruments 可以看到内存地址首先在 clusterAnnotations 中进行了 Malloc 处理，然后被保留并释放了几次，然后被 regionQueryForPoint 保留了很多次（达到 47 个引用的峰值），然后被 clusterAnnotations 释放了两次，然后由 [NSAutoreleasePool drain] 释放，直到引用计数达到 -1 并且我收到僵尸消息错误。这是 regionQueryForPoint 的代码：
- (NSSet *)regionQueryForPoint:(NSMutableDictionary *)P andEpsilon:(float)eps fromList:(NSMutableSet *)D
{
NSMutableSet *N = [[[NSMutableSet alloc] init] autorelease];
for (NSMutableDictionary *dictEntry in D)
{
if ((dictEntry != P) &&
([[dictEntry objectForKey:@"point"] isKindOfClass:[PostLocationAnnotation class]]))
{
CGPoint p1 = [ffMapView convertCoordinate:[[P objectForKey:@"point"] coordinate] toPointToView:self.view];
CGPoint p2 = [ffMapView convertCoordinate:[[dictEntry objectForKey:@"point"] coordinate] toPointToView:self.view];
float dX = p1.x - p2.x;
float dY = p1.y - p2.y;
if (sqrt(pow(dX,2)+pow(dY,2)) < eps)
{
[N addObject:dictEntry];
}
}
}
return (NSSet *)N;
}
当从 expandDbScanClusterWithPoint 方法调用 regionQueryForPoint 时，似乎会发生大量保留，因此为了完整起见，我将其包含在此处：
- (void)expandDbscanClusterWithPoint:(NSMutableDictionary *)P andRegion:(NSMutableSet *)N
andCluster:(LocationGroupAnnotation *)cluster
andEpsilon:(float)eps
andMinPts:(int)minPts
fromList:(NSMutableSet *)D
{
[cluster addAnnotation:(PostLocationAnnotation *)[P objectForKey:@"point"]];
[P setValue:[NSNumber numberWithBool:YES] forKey:@"clustered"];
BOOL finished = NO;
while (!finished)
{
finished = YES;
for (NSMutableDictionary *nextP in N)
{
if ([nextP objectForKey:@"visited"] == [NSNumber numberWithBool:NO])
{
[nextP setValue:[NSNumber numberWithBool:YES] forKey:@"visited"];
NSSet *nextN = [self regionQueryForPoint:nextP andEpsilon:eps fromList:D];
if ([nextN count] >= minPts)
{
[N unionSet:nextN];
finished = NO;
break;
}
}
if ([nextP objectForKey:@"clustered"] == [NSNumber numberWithBool:NO])
{
[cluster addAnnotation:[nextP objectForKey:@"point"]];
[nextP setValue:[NSNumber numberWithBool:YES] forKey:@"clustered"];
}
}
}
}
我已经剖析这个很久了，计算引用，观察指针和所有东西，但我就是不知道如何安全地释放这个 D 集。谁能看到我没看到的东西？