iOS中的mkmapview图像叠加缩放内存问题

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...