If I use a generic/aftermarket iPhone USB cable instead of the official Apple product, can it damage the iPhone? A vendor at the mall said that high quality iPhone USB cables have a chip that regulates the charging current so it won't damage the device. He said the cheaper cables don't have that capability. Doesn't sound very credible, so I wanted to double check.
They are generally safe to use. And they don't have a chip (at least the ones I've used).
The charger itself may regulate the current, but the cable itself doesn't. I've used a multitude of cables from a multitude of vendors over the years and I've never had a problem with damaging devices. Build quality is a different matter. Too cheap, and the cables inside can break. Rare but does/can happen.
Hypothetically the answer is yes - but - for all practical purposes you will never have to worry. One could somehow "rig" up a malicious USB cable that did something funky - but - one you would buy from a 3rd party should never hurt your phone (although the cable might not last too long)
If its MFI Certified that means its Non-Apple but Apple approved. These cablers will be more expensive than the total knock-offs from china.