Objective-C MapKit Overlay on entire map - ios

Question

How would I create an overlay that colors the entire map a certain color? Then I need to be able to place annotations on top of it. Any ideas? Thanks.

Answer 1

What you want is MKOverlay and MKOverlayView.
You can find apple's code in one of the apps mentioned in 'Related sample code'. in above protocol and class reference page.
EDIT : As Per the comments previous code was not working as-is. Heres a MKMapDimOverlay GitHub project which you can simply integrate using CocoaPods. I have also made the relevant changes in following code in the answer.
To explain briefly, following is code for adding a dark overlay on entire map.
You need to create an overlay and add it to the map view.
MKMapDimOverlay *dimOverlay = [[MKMapDimOverlay alloc] initWithMapView:MapView];
[mapView addOverlay: dimOverlay];
Create and return MKOverlayView for the specific MKOverlay in 'viewForOverlay' delegate method
-(MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay {
if([overlay isMemberOfClass:[MKMapDimOverlay class]]) {
MKMapDimOverlayView *dimOverlayView = [[MKMapDimOverlayView alloc] initWithOverlay:overlay];
return dimOverlayView;
}
}
Since all you want is a colored overlay covering the map, your overlay and overlay view implementation will be very simple.
DimOverlay.m
#interface DimOverlay ()
#property (nonatomic) CLLocationCoordinate2D dimOverlayCoordinates;
#end
#implementation DimOverlay
-(id)initWithMapView:(MKMapView *)mapView {
self = [super init];
if(self)
{
self.dimOverlayCoordinates = mapView.centerCoordinate;
}
return self;
}
-(CLLocationCoordinate2D)coordinate {
return self.dimOverlayCoordinates;
}
-(MKMapRect)boundingMapRect {
return MKMapRectWorld;
}
#end
DimOverlayView.m
#implementation DimOverlayView
- (void)drawMapRect:(MKMapRect)mapRect
zoomScale:(MKZoomScale)zoomScale
inContext:(CGContextRef)ctx {
/*
You can allow custom colors and opacity values.
Simply add UIColor and CGFloat properties in the overlay view class
and use those properties instead of the default hardcodes values below.
*/
CGContextSetAlpha(ctx, 0.85);
CGContextSetFillColorWithColor(ctx, [UIColor blackColor].CGColor);
CGContextFillRect(ctx, [self rectForMapRect:mapRect]);
}
#end