Ignore query params with SDWebImage

Question

I'm using SDWebImage to cache images in my app, however I recently ran into a problem where images that should be cached keep refreshing. Looking into it I found that the full image url from AWS is actually changing due to parameters tacked onto the end of the url. Every time I fetch the object that contains the image url, the image url returns with a dynamic "signature" and "expires" parameter (for security purposes). A different url so far as the image cache is concerned, but notice the same path to the image.

First fetch:

https://myapp.s3.amazonaws.com/path/image123.jpeg?AWSAccessKeyId=SOMEKEY&Signature=vrUFlMFEQ9fqQ%3D&Expires=1441702633

Fetch again 1 second later:

https://myapp.s3.amazonaws.com/path/image123.jpeg?AWSAccessKeyId=SOMEKEY&Signature=2mcMxUJLyJd7E%3D&Expires=1441703105

What's the best way to handle this situation? Sure would be awesome if SDWebImage had an option to ignore query params beyond the path to the file.

Answer 1

iOS 14 || Swift 5

SDWebImageManager.shared.cacheKeyFilter = SDWebImageCacheKeyFilter { url in
    var components = URLComponents(url: url, resolvingAgainstBaseURL: false)
    components?.query = nil

    print("SDWebImage Cache Key:", components?.url)

    return components?.url?.absoluteString ?? ""
}

So configure SDWebImageManager at launch & then whenever a url is supplied, it will be stripped of all it's query parameters to generate a common cache key identifier for SDWebImage cache logic to work properly again.

So something like:

https://bucket.s3.us-east-1.amazonaws.com/public/someAsset.ext?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=TILT&X-Amz-Date=20210602T113954Z&X-Amz-Expires=17999&X-Amz-SignedHeaders=host&X-Amz-Security-Token=TILT&X-Amz-Signature=TILT

will have the cache key:

https://bucket.s3.us-east-1.amazonaws.com/public/someAsset.ext

---

NOTE: Pay attention to the final url. If the url is dependent on its query parameters for a dynamic output then obviously you will need to modify the logic in SDWebImageCacheKeyFilter to fit your requirement.

Answer 2

SDWebImage has a method that allows for using a custom key, which helps in this case as AWS changes the query every time it's called.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary    *)launchOptions
{
    SDWebImageManager.sharedManager.cacheKeyFilter = ^(NSURL *url) {
        url = [[NSURL alloc] initWithScheme:url.scheme host:url.host path:url.path];
        return [url absoluteString];
    };

    // Your app init code...
    return YES;
}

For more reading: SDWebImage | Using the cache key filter

Answer 3

@John 's answer is very good, but I met sometimes crashed.

below is more stable version.

SDWebImageManager.sharedManager.cacheKeyFilter = ^(NSURL *url) {
    if( [[url absoluteString] isEqualToString:@""] ){
        return @"";
    }
    url = [[NSURL alloc] initWithScheme:url.scheme host:url.host path:url.path];
    return [url absoluteString];
};

This additional code checks if url is valid. [[NSURL alloc] initWithString:@""] or something like this makes crashes.