Minecraft – Error when trying to transfer Minecraft worlds from iOS to PC

One work around is to run your own Minecraft server. The a dis-advantage this the Nether isn't currently working. You can launch the Minecraft server to load single player worlds. Just find your old ./world# folder in your .minecraft directory. When launching the server be sure your world matches the world name in the server.properties file.

I believe Mojang mentioned going this route in the future with Single player. Having the client launch a server instance locally and connect to it.

When this is fixed in future versions it should be a simple copy of the ./world folder back to your .minecraft directory and you will be able to load the world normally again.

You can't move the folder away from where Minecraft keeps it – Minecraft won't know where you put it and will just assume you've deleted your saves.

You need to put it back in your "minecraft folder" which is in [home]/Library/Application Support/minecraft/.

However, you probably can't find that location easily because Library is a hidden folder. The easiest way to find it then is to open Minecraft, log in, click Options… → Resource Packs → Open resource packs folder. This will open a Finder window showing you a (probably empty) folder. With this Finder window at the front, press ⌘+↑. That will navigate up into your Minecraft folder. Put your saves folder here, so that there is the minecraft folder with a saves folder inside it, with your worlds inside that.

If you want to be able to find your saves easily still, right-click the saves folder and choose "alias". This will make a shortcut that you can move anywhere you want.