There are some paid apps like dr.fone or BackupTrans that can transfer things like WhatsApp message history directly from Android phones to iPhones. Normally, I'd say they copy the message store DB and key file from Android via ADB and then store it in the respective path on iOS. But how do they access the file system of a (non-jailbroken) iPhone? Do they use some kind of exploit or is there another, official way to do that?