From e9909f7ddd47577126713178b6f90fa7886df3ec Mon Sep 17 00:00:00 2001
From: Charles Niaulin <cniaulin@gmail.com>
Date: Tue, 24 Jul 2012 18:36:30 +0200
Subject: [PATCH] center cluster coordinate according to clustered pins

---
 OCMapView/OCAnnotation.m | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/OCMapView/OCAnnotation.m b/OCMapView/OCAnnotation.m
index 98b8a12..d501450 100644
--- a/OCMapView/OCAnnotation.m
+++ b/OCMapView/OCAnnotation.m
@@ -65,6 +65,11 @@ - (NSArray *)annotationsInCluster{
 - (void)addAnnotation:(id < MKAnnotation >)annotation{
     [annotation retain];
     
+    //calculate new cluster coordinate
+    float annotationCount = (float)[annotationsInCluster count];
+    coordinate.latitude = (coordinate.latitude * annotationCount + annotation.coordinate.latitude) / (annotationCount + 1);
+    coordinate.longitude = (coordinate.longitude * annotationCount + annotation.coordinate.longitude) / (annotationCount + 1);
+    
     // Add annotation to the cluster
     [annotationsInCluster addObject:annotation];
     [annotation release];
@@ -81,6 +86,11 @@ - (void)addAnnotations:(NSArray *)annotations{
 - (void)removeAnnotation:(id < MKAnnotation >)annotation{
     [annotation retain];
     
+    //calculate new cluster coordinate
+    float annotationCount = (float)[annotationsInCluster count];
+    coordinate.latitude = (coordinate.latitude * annotationCount - annotation.coordinate.latitude) / (annotationCount - 1);
+    coordinate.longitude = (coordinate.longitude * annotationCount - annotation.coordinate.longitude) / (annotationCount - 1);
+    
     // Remove annotation from cluster
     [annotationsInCluster removeObject:annotation];