In the question Can I feed my cat whenever she wants? the OP feeds dry cat food, but is not able to leave the food out all the time as ants are an issue.
Is it possible to place dry cat food so the cat can get it but the ants can't?
tl;dr- Get a moat that goes around the food. Ants usually won't go through water. One simple approach is to put a plate underneath the food bowl, then some water on the plate.
"Ant-Proof Pet Food Bowl", instructibles, shows a few ways to add a moat yourself. They show the concept as:
You can make something like this yourself, such as by putting a plate underneath a food bowl, or purchase a commercial solution.
There're a few issues to be aware of:
Larger ants require larger moats. If used outdoors, you're more likely to have problems with larger ants that can step over thin moats or walk through shallow moats. So, larger moats are more appropriate outdoors.
Animals may try to drink the moat. This isn't necessarily a problem; some setups actually intend to use the same body of water for both a moat and the animal's water bowl.
Animals may scatter food into the moat, which can be messy and unhealthy if the animal also drinks from the moat. A covered moat can help improve this problem, though cleaning and care are probably required in most cases.
If the moat's stagnant water, it'll have to be cleaned to avoid molding.
Note: This contains commercial links to Amazon.com. This isn't meant as an endorsement, but rather just to survey of some advertised solutions. I have no commercial affiliation with either Amazon.com or the linked products.
One approach is a raised feeder, as shown in the product "BugSnub Ant Proof Raised Feeder for Cats and Small Dogs with Stainless Steel Bowl" on Amazon.com:
This approach tries to avoid using a water moat. Or, I'd assume, you could put the base in water. Whatever the case, it demonstrates that a "moat" is any sort of barrier that prevents ants from having a viable path to the food; it doesn't necessarily need to involve water.
Another solution is this "The 3-in-1 Ant Free Pet Dish" on Amazon.com:
This is an example of a solution that uses the same body of water for both the pet's water source and the moat. Oddly enough, it's also a good example of how the moat can be covered to prevent the pet from drinking it - though it loses that quality by then connecting the moat to the pet's intended water bowl. One review on Amazon.com suggested that larger ants could get over the moat in this case.
There're a lot more interesting solutions on Amazon.com beyond the above quick examples.