Accessories for my Iphone 5s not working?

My Iphone 5s chargers have been giving me problems. First my regular cable that came with the phone works fine. I go out and buy a charger thats longer from the store so I have more cord. When I plug it in it says "this cable or accessory is not certified and may not work reliably with this iphone". I also bought a case that charges the phone and have the same problems along with the same thing with other cords I have bought. Also bought a charger that worked that was 9 ft long that stopped working a couple days after I got it, this was not a cheap cord almost 30 bucks. My main question is why are the devices saying it's not certified? They say they work for the Iphone 5. But I wonder if its only the 5c they work for and not the 5s. I just don't want to make the mistake of buying anything else for this damn phone if it's just not going to work. Please advice needed.

Apple now requires Lightning cable manufacturers to include a chip in the port, but that was not always the case. Unlike nearly every other smartphone manufacturer, Apple has spurned chargers with USB micro ports, instead opting for its proprietary Lightning port. According to a recent New York Times article, this allows the company to tightly control Apple accessories.