public protocol RSDImageWrapperDelegate
RSDImageWrapperDelegate is a singleton delegate that can be used to customize the rules for fetching
an image using the
RSDImageWrapper. If defined and attached to the
RSDImageWrapper using the static property
sharedDelegate then the image wrapper will ask the delegate for the appropriate image.
Get an image of the appropriate size.
The size of the image to return.
The name of the image
The callback with the image, run on the main thread.