A struct encapsulating progress information, as well as useful helper methods.
The number of bytes that have been transferred.
The total number of transferrable bytes (bytes that have been transferred, plus bytes pending transfer).
If the notification block is tracking downloads, this number represents the size of the changesets generated by all other clients using the Realm. If the notification block is tracking uploads, this number represents the size of the changesets representing the local changes on this client.
The fraction of bytes transferred out of all transferrable bytes. If this value is 1, no bytes are waiting to be transferred (either all bytes have already been transferred, or there are no bytes to be transferred in the first place).
Whether all pending bytes have already been transferred.