One of the best file transfer tool between Mac & iOS devices. FileDrop is much easier to use than DropCopy, since you won't need to configure anything at all.
FileDrop a standard application, so that you just have to launch, connect, transfer file, and quit, that's it. And that's why I like it over DropCopy: for most of the time yon won't need to have a persistent service waiting for connection all the time.
For those who have trouble pairing devices: first check the version of FileDrop on each ends. Then make sure all devices are connected in the same "broadcast domain". Please note that two devices may not be in the same broadcast domain even their subnet number is identical. And some routers or WiFi APs may sometimes blocks certain broadcast pockets (such as mDNS used by Bonjour.) You may consult with your network administrator for this. If still fails, there might be something "chattery" in your local network, such as DLNA.