Whenever I spray any ivy with glysophate weedkiller it just seems to kill what part has been sprayed so can't see how salt could do the trick unless you were doing it every day... In my opinion the only way to do it is to pull it up.
ivy is virtually indestructible I'm afraid. Short of completely digging out the roots you'll never get rid of it. Even the slightest little bit of root left in the soil will have a mind of its own and start regenerating. Believe me, I've been trying for 20 years to erradicate ivy intruding from our next door neighbour's garden and having tried virtually every method under the sun I haven't yet succeeded.