Regions/RegionAnnotationView.m

/*
     File: RegionAnnotationView.m
 Abstract: This is a custom MKAnnotationView that handles updating and removing the radius overlay to show where the region surrounding an annotation is.
  Version: 1.1
 
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 */
 
#import "RegionAnnotationView.h"
#import "RegionAnnotation.h"
 
@implementation RegionAnnotationView
 
@synthesize map, theAnnotation;
 
- (id)initWithAnnotation:(id <MKAnnotation>)annotation {
    self = [super initWithAnnotation:annotation reuseIdentifier:[annotation title]];    
    
    if (self) {     
        self.canShowCallout = YES;      
        self.multipleTouchEnabled = NO;
        self.draggable = YES;
        self.animatesDrop = YES;
        self.map = nil;
        theAnnotation = (RegionAnnotation *)annotation;
        self.pinColor = MKPinAnnotationColorPurple;
        radiusOverlay = [MKCircle circleWithCenterCoordinate:theAnnotation.coordinate radius:theAnnotation.radius];
        
        [map addOverlay:radiusOverlay];
    }
    
    return self;    
}
 
 
- (void)removeRadiusOverlay {
    // Find the overlay for this annotation view and remove it if it has the same coordinates.
    for (id overlay in [map overlays]) {
        if ([overlay isKindOfClass:[MKCircle class]]) {                     
            MKCircle *circleOverlay = (MKCircle *)overlay;          
            CLLocationCoordinate2D coord = circleOverlay.coordinate;
            
            if (coord.latitude == theAnnotation.coordinate.latitude && coord.longitude == theAnnotation.coordinate.longitude) {
                [map removeOverlay:overlay];
            }           
        }
    }
    
    isRadiusUpdated = NO;
}
 
 
- (void)updateRadiusOverlay {
    if (!isRadiusUpdated) {
        isRadiusUpdated = YES;
        
        [self removeRadiusOverlay]; 
        
        self.canShowCallout = NO;
        
        [map addOverlay:[MKCircle circleWithCenterCoordinate:theAnnotation.coordinate radius:theAnnotation.radius]];    
        
        self.canShowCallout = YES;      
    }
}
 
 
- (void)dealloc {
    [radiusOverlay release];
    [super dealloc];
}
 
 
@end