iPhone ↔ iPad connected to same iCloud account

To share saves between iPad and iPhone that are bound to same iCloud there are save/load buttons on the main screen, so it's easy-peasy.

Mac/PC ↔ iPhone/iPad

Mac/PC → iPhone/iPad

iCloud way

1. Grab graveyard, memorial and save directories from your user's Cataclysm folder (/Users/UserName/Library/Application Support/Cataclysm on mac, C:\Users\UserName\AppData\Local\VirtualStore\Program Files (x86)\Cataclysm for Windows, where UserName is you user's name).
2. Zip them into an archive and name it save.zip. Note that you may put other files and directories (into the archive, but they won't be loaded to your iPhone/iPad in order not to break things, especially config directory might be sensitive.
3. Copy/upload this archive into your Cataclysm RPG directory in your iCloud.
4. Run the game and navigate to the start screen, where play/load/save buttons are.
5. Tap "Load from iCloud" button, wait until the message "Load successful" appears.
6. Tap "Play" and you should see your saved worlds and characters available under "Load game".

iTunes way

1. Grab any directories you like from your user's Cataclysm folder (/Users/UserName/Library/Application Support/Cataclysm on mac, C:\Users\UserName\AppData\Local\VirtualStore\Program Files (x86)\Cataclysm for Windows, where UserName is you user's name).
2. Copy them into Cataclysm RPG directory on your iPhone/iPad using iTunes interface, replacing existing directories accordingly.
3. Run the game and navigate to the start screen, where play/load/save buttons are.
4. Tap "Play" and you should see your saved worlds and characters available under "Load game".

iPhone/iPad → Mac/PC

iCloud way

1. Run the game and navigate to the start screen, where play/load/save buttons are.
2. Tap "Save to iCloud", wait until "Upload completed" appears.