Removing the prefetcher's output logging.

[jparise]

While useful during development, there isn't a benefit to having this
logging in a production build.

This class already exposes enough information for this type of logging
(or similar instrumentation) to be implemented externally, perhaps
with a wrapper class, for those applications that need it.

[andyvb]

👍

[rs]

Would be nice to keep it in DEBUG macro conditions.

[jparise]

I considered keeping it for DEBUG, but it still felt too noisy for that environment. (I often prefetch 50+ images) That's a matter of personal opinion, of course.

If you feel strongly about retaining some level of debug-level output, I think a good compromise would be logging only the summary line in DEBUG builds.

[andyvb]

I would prefer to be able to turn it on or off, perhaps via a property. Even in debug I don't always want to see logging. Since you already have a way to call it with a completion block, a developer could use that instead (granted it would require a recompile). Or maybe add a method signature which returns an NSError for a failure case, since other than count for success it's the only additional info one might usually care about.

[pieterclaerhout]

Have a look at #577.

This pull request adds a delegate for the image prefetcher. This way, everybody can choose what he/she thinks is the best approach.

[bpoplauschi]

Fixed by #551 plus #721, same as #499