Hmm, why set `taskDictionary[urlString] = nil` at the bottom there? If the whole point is to cache the result, isn't the point to leave the value there for other requests to pick it up?
Yup, nice catch, no need to reset it to nil if you wanna keep it in memory indefinitely.
I guess making it nil can be also used if you don't wanna make the same request when there is one already in flight, in case you have a 403 error and need to request a refresh token, you don't wanna make two simultaneous requests, but you also don't wanna catch it indefinitely either.
