Remove all the annotation pin except one - ios

Question

I have a cluster of annotation pins in map view. When I clicked on the pin I get the index of that pin. I want that if I click on the pin than all the pins are hide except that on which user clicked and if again I click on that pin all the pins are shown.
Here is the code in which I got the index of the selected pin.
CPointAnnotation *cAnno=(CPointAnnotation*)view.annotation;
NSInteger index=cAnno.index;
if (index<hospitalsArry.count) {
selectedHospital=[hospitalsArry objectAtIndex:index];
if (selectedIndex==index) {
selectedIndex=-1;
return;
}else{
selectedIndex=index;
[[self.mapView viewForAnnotation:cAnno] setHidden:NO];
}

Answer 1

CustomAnnotation.h
#import <MapKit/MapKit.h>
#interface CustomAnnotation : NSObject <MKAnnotation>
#property (nonatomic,readonly)CLLocationCoordinate2D coordinate;
#property (nonatomic, copy)NSString *title;
#property (nonatomic, strong)MKAnnotationView *annotaitonView;
-(id)initWithTitle:(NSString *)newTitle coordinates:(CLLocationCoordinate2D)newCoordinate;
-(MKAnnotationView *)createAnnotationView;
#end
CustomAnnotation.m
#implementation CustomAnnotation
-(id)initWithTitle:(NSString *)newTitle coordinates:(CLLocationCoordinate2D)newCoordinate
{
if (self = [super init]) {
_title = newTitle;
_coordinate = newCoordinate;
}
return self;
}
-(MKAnnotationView *)createAnnotationView
{
MKAnnotationView *annView=[[MKAnnotationView alloc]initWithAnnotation:self reuseIdentifier:#"MyCustomAnnoation"];
annView.enabled=TRUE;
annView.canShowCallout=TRUE;
annView.image=[UIImage imageNamed:#"map-pin-marker-circle-128.png"];
return annView;
}
#end
in MapViewController.m
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {
if ([annotation isKindOfClass:[MKPointAnnotation class]]) {
return nil;
}
if ([annotation isKindOfClass:[CustomAnnotation class]]) {
CustomAnnotation *myAnn=(CustomAnnotation *)annotation;
MKAnnotationView *annView=[mapView dequeueReusableAnnotationViewWithIdentifier:#"MyCustomAnnoation"];
if (annView == nil) {
annView=[myAnn createAnnotationView];
}
else
{
annView.annotation=myAnn;
}
myAnn.annotaitonView=annView;
return annView;
}
else
return nil;
}
-(void)mapView:(MKMapView *)mapView didSelectAnnotationView:(MKAnnotationView *)view
{
[self hideOtherPinsByIgnoringThis:view];
}
-(void)hideOtherPinsByIgnoringThis:(MKAnnotationView *)ann
{
NSArray *arrAllPins=[self.myMapView annotations];
//Find selected Annotation View in all pins on map
NSMutableArray *removeAnn=[[NSMutableArray alloc]init];
for (CustomAnnotation *annotation in arrAllPins)
{
if (annotation.annotaitonView != ann) {
[removeAnn addObject:annotation];
}
}
[self.myMapView removeAnnotations:removeAnn];
}