@Maaza : Save states don’t seem to be compatible, but most save files work fine (save your game normally before transfer)…
You can use iExplorer (or iFunBox), and find the save files in :
Provenance -> Documents -> Battery States -> (YourGameName)
Copy them first from the (YourGameName) folder, then transfer them to :
RetroArch -> Documents -> saves
If the cores use compatible save formats, it will work !
Note that your save file must have the same name as a save created by RetroArch, if you’re not sure, you can start the game first in RetroArch, and then see the actual name of the newly created save file, and it’s file extension…
For exemple, I just tried with Baldur’s Gate - Dark Alliance on GBA, I had to rename the save from “Baldur’s Gate - Dark Alliance.sav2” (from Provenance VBAM core) to “Baldur’s Gate - Dark Alliance.srm” (RetroArch mGBA core), and it worked fine !