Animated gif not working in MKMapView overlay using MKOverlayRenderer

Question

I am trying to display an animated gif in an overlay for MKMapView. The overlay is created using the MKOverlayRenderer. To animate the gif in iOS 7, I'm using the UIImage+animatedGIF category posted here on GitHub.

The image of the animated gif displays fine in the overlay using the category; however, the gif does not animate. I have no problem using the category to animate a gif in a UIImageView but it does not seem to work correctly in a map view overlay.

How can I use this category to place an animated gif in a map view overlay?

or...

Is there a way to place a UIImageView in the overlay which might solve my problem by setting the UIImageView with the animated gif?

My overlay renderer subclass is the following:

MapOverlayRenderer.h

#import <MapKit/MapKit.h>

@interface MapOverlayRenderer : MKOverlayRenderer
- (instancetype)initWithOverlay:(id<MKOverlay>)overlay overlayImage:(UIImage *)overlayImage;
@end

MapOverlayRenderer.m

#import "MapOverlayRenderer.h"

@interface MapOverlayRenderer ()
@property (strong,nonatomic) UIImage *image;
@end

@implementation MapOverlayRenderer

- (instancetype)initWithOverlay:(id<MKOverlay>)overlay overlayImage:(UIImage *)overlayImage {

    self = [super initWithOverlay:overlay];

    if (self) {
        _image = overlayImage;
    }

    return self;
}

- (void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CGContextRef)context {

    CGImageRef imageReference = self.image.CGImage;

    MKMapRect theMapRect = [self.overlay boundingMapRect];
    CGRect theRect = [self rectForMapRect:theMapRect];

    CGContextScaleCTM(context, 1.0, -1.0);
    CGContextTranslateCTM(context, 0.0, -theRect.size.height);

    CGContextDrawImage(context, theRect, imageReference);    
}

@end

In my UIViewController, I am fetching the animated gif and adding the overlay by calling a method which contains the following code:

NSURLSession *session = [NSURLSession sharedSession];

    [[session dataTaskWithURL:[NSURL URLWithString:radarUrl] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        self.radarImage = [UIImage animatedImageWithAnimatedGIFData:data];  //for animated radar image

        dispatch_async(dispatch_get_main_queue(), ^{

            [self.mapView addOverlay:self.polygon];

        });

    }] resume];

Any suggestions on how to animate a gif in an iOS 7 map view overlay would be greatly appreciated.

Answer 1

Because a map view overlay is having your draw in a CGContext, it won't animate -- that is a buffer which is drawn to and translated to view contents, as opposed to being a normal part of the view hierarchy. Unfortunately you will need to make use of -setNeedsDisplayInMapRect:zoomScale: repeatedly to request animations. This system is a bit less flexible than iOS 6 and before, which added normal views atop the map.

Answer 2

https://github.com/jhurray/iOS7AnimatedMapOverlay

this is the best way to animate overlays in iOS7