Manage memory allocation issue on Map iOS - memory-management

Question

In my iPhone app I have a map view. In this I am displaying a number of pin views depends on the data from a web server. Here is the method I used for it.
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{
NSString *identifier = #"myPin";
self.pinView = (MKPinAnnotationView *)[self.mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
if (self.pinView == nil) {
self.pinView= [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier]autorelease]; //11.1%
} else {
self.pinView.annotation = annotation;
}
UIButton* rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure]; //20.4%
[rightButton setTitle:annotation.title forState:UIControlStateNormal];
self.pinView.rightCalloutAccessoryView = rightButton; //2.7%
MyAnnotation *annot = (MyAnnotation*)annotation;
UIImageView *egoimageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"defaultPerson"]]; //17.5%
NSString *imageUrl = [NSString stringWithFormat:#"%#%#", CommonImageURL, [friendsProfileImageArray objectAtIndex:annot.tag]]; //9.4%
if ([[UIScreen mainScreen] respondsToSelector:#selector(displayLinkWithTarget:selector:)] &&
([UIScreen mainScreen].scale == 2.0)) {
// Retina display
[egoimageView setImageWithURL:[NSURL URLWithString:imageUrl] placeholderImage:[UIImage imageNamed:#"defaultPerson#2x.png"]]; //2.6%
egoimageView.image = [UIImage imageWithCGImage:egoimageView.image.CGImage scale:egoimageView.image.size.width/25 orientation:egoimageView.image.imageOrientation];
} else {
// non-Retina display
[egoimageView setImageWithURL:[NSURL URLWithString:imageUrl] placeholderImage:[UIImage imageNamed:#"defaultPerson.png"]]; //14.6%
egoimageView.image = [UIImage imageWithCGImage:egoimageView.image.CGImage scale:egoimageView.image.size.width/25 orientation:egoimageView.image.imageOrientation]; //1.6%
}
[egoimageView sizeToFit];
self.pinView.leftCalloutAccessoryView = egoimageView; //3.1%
[egoimageView release];
self.pinView.canShowCallout=YES;
self.pinView.animatesDrop=YES;
//pin color based on status.....
if ([annot.relationshipStatus intValue]==2 )
self.pinView.pinColor=MKPinAnnotationColorGreen;
else
self.pinView.pinColor=MKPinAnnotationColorPurple; //17.1%
return self.pinView;
}
In this I have mentioned the percentage of memory allocations. If I continuously load the map, the total memory usage increases and the app crashes. How can I properly fix this? I have tried to fix it, but I don't know what more I can do.
Please help, thanks in advance.