- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation

UIButton *btn = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
[btn addTarget:self action:@selector(pinTouched:) forControlEvents:UIControlEventTouchUpInside];

-(void)pinTouched:(UIButton *)sender
{
myView.transform  = CGAffineTransformMakeScale(.01, .01);
[self.view addSubview:myView];
}