Why is my iPhone still not charging?

I was using my iPhone normally to watch Netflix yesterday, and as soon as the battery was starting to die, I plugged in the iPhone to the charger. I soon found out that my iPhone wasn't charging anymore. In order to diagnose it, I started with the basic and that was to see if it was my wall charger or my cable that was causing the problem or not. This was not the problem because the wall charger and cable worked with another iPhone. Soon after, I tested the headphone jack, speakers and the microphone and it was working fine. I continued by swapping out the battery for a new one and it still didn't solve the problem. I also tried swapping out the dock connector and the problem still didn't disappear but what was weird was that when I would plug in the lightning cable into the dock, it would turn on the iPhone and it would recognize the iPhone on the computer but it wasn't charging. I would think it was the dock, but I swapped out 2 docks and still didn't work. If you know how I could fix this, please let me know! Thank you!