IPhone won't charge while in use?

So I recently bought an iPhone 6 and before this I had an iPhone 5c. I've noticed that if my iPhone is plugged into the charger it won't charge if I'm using it. Its not a huge issue for me but I thought it was strange because that has never happened with my old iPhone or any phone I've ever had before. So is there a way to fix that?

It's most likely a faulty charge cable or the charger itself - or the charger is simply not high enough current rating (eg. 0.5A rather than 1A or 2A).

The screen takes quite a bit of power when it's on; if that is all the charger can give, there's not enough to charge the battery at the same time.

1. Make sure that you are using the cable and wall charger that came with your iPhone 6. If the charger or cable you're trying to use isn't Apple certified then that could be your problem right there.
2. Try using a different wall socket, a different cable, and a different charger.
3. Take a look at the connector on your cable and the port on your iPhone. Make sure that they're clean and free of dust. You can blow or blast a little compressed air into the port to clean it out.
4. Try resetting your device while it's plugged into the charger by holding down the Sleep/Wake and Home buttons for 10 seconds or so until the Apple logo appears.
Hope it works.