mkmapview image overlay zooming Memory issue in ios - ios

Question

When I am adding a imageOverlay with high resolution image and map zooms image in the map gone and got memory issues.some times my app crashes. How can this be solved?
Here is my code
-(void)addOverlay
{
MapOverlay *overlay = [[MapOverlay alloc] initWithRouteOverlay:self.routeOverlayObj];
[self.mapView addOverlay:overlay];
}
- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay
{
if([overlay isKindOfClass:[MapOverlay class]])
{
mapOverlay = (MapOverlay *)overlay;
NSLog(#"%# %#",routeInfoObj.routeOverlay,[UIImage imageNamed:routeInfoObj.routeOverlay]);
ATTMapOverLayRender *mapOverlayRender = [[ATTMapOverLayRender alloc] initWithOverlay:mapOverlay overlayImage:[UIImage imageNamed:routeInfoObj.routeOverlay] andImageFile:[NSString stringWithFormat:#"%#.png",routeInfoObj.routeOverlay]];
return mapOverlayRender;
}
else
{
MKPolylineRenderer *routeRenderer = [[MKPolylineRenderer alloc] initWithPolyline:routePolyline];
routeRenderer.strokeColor = [UIColor redColor];
routeRenderer.fillColor = [UIColor redColor];
routeRenderer.lineWidth = 5;
return routeRenderer;
}
return nil;
}
and in "ATTMApOVerlayRender.h"
#interface ATTMapOverLayRender : MKOverlayRenderer
- (instancetype)initWithOverlay:(id<MKOverlay>)overlay overlayImage:(UIImage *)overlayImage andImageFile:(NSString *)file;
#property (nonatomic, weak) UIImage *overlayImage;
#end
"ATTMApOVerlayRender.h"
#import "ATTMapOverLayRender.h"
#implementation ATTMapOverLayRender
- (instancetype)initWithOverlay:(id<MKOverlay>)overlay overlayImage:(UIImage *)overlayImage andImageFile:(NSString *)file {
self = [super initWithOverlay:overlay];
if (self) {
self.overlayImage = overlayImage;
}
return self;
}
- (void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CGContextRef)context {
CGImageRef image = _overlayImage.CGImage;
MKMapRect overlayMapRect = [self.overlay boundingMapRect];
CGRect overlayRect = [self rectForMapRect:overlayMapRect];
// draw image
CGContextScaleCTM(context, 1.0, -1.0);
CGContextTranslateCTM(context, 0.0, -overlayRect.size.height);
CGContextDrawImage(context, overlayRect, image);
}
#end

Answer 1

I'm running into similar problems on a tile overlay project as well.
I was able to significantly improve the memory usage by maintaining a single MKMapOverlayRenderer.
Rather than allocating memory for a new MKOverlayRenderer (or MKPolylineRenderer) every time the mapView: renderForOverlay: method is called, create a class variable and rewrite to it.
So in your ViewController.h or whatever class contains your mapView that calls -(MKOverlayRenderer*)mapView:(MKMapView*)mapView rendererForOverlay:(id<MKOverlay>)overlay have,
#property (nonatomic, strong) MKOverlayRenderer *renderer;
And in the declaration of -(MKOverlayRenderer*)mapView:(MKMapView*)mapView rendererForOverlay:(id<MKOverlay>)overlay
use
self.renderer = [[MKOverlayRenderer alloc] init...