Passing non-default ImageProcessor to ImagePrefetcher will always cause cache miss

[Killectro]

When you pass an ImageProcessor to ImagePrefetcher it will check to see if it exists in the cache like this:

let alreadyInCache = manager.cache.isImageCached(forKey: resource.cacheKey).cached

If that returns false it will continue on, download the image, process it, and store it like this:

targetCache.store(image,
                  original: originalData,
                  forKey: key,
                  processorIdentifier:options.processor.identifier,
                  cacheSerializer: options.cacheSerializer,
                  toDisk: !options.cacheMemoryOnly,
                  completionHandler: nil)

Both cache keys are calculated using the same method:

let computedKey = key.computedKey(with: identifier)

but you might notice, that above when calling the isImageCached(forKey:processorIdentifier:) method, ImagePrefetcher doesn't pass the processorIdentifier: parameter. This means that if the URL is example.com, ImagePrefetcher is checking (the md5 hash of) example.com to see whether there is a cached version, but when it goes to download and store the image, it is storing it at example.com@<processor_name>. This means that the ImageProcessor will never have a cache hit if you pass anything other than DefaultImageProcessor as an option.

This can be remedied by simply passing the processorIdentifier: parameter as such:

let alreadyInCache = manager.cache.isImageCached(forKey: resource.cacheKey, processorIdentifier: optionsInfo.processor.identifier).cached

I will open a PR by EOD today that fixes this bug.

[onevcat]

You are definitely correct on this! Thank you!

[onevcat]

Should be fixed in version 3.4.0.