After iOS7 upgrade Apple have added functionality to detect non-OEM accessories being connected to apple devices. its kind of enforcement to use “Certified Apple Accessories” . and this is the only reason why i am not a big fan of Apple products.
Anyhow this is not the case every time, few days back one of my colleague called me late night, and told me he is getting this message pop up error. i was surprised too as his iPhone 6 plus is just a month old. he have 2 iPhone  and he swapped the charging cables & chargers too, but didn’t resolved the issue even though cable & chargers were original.
as i never used an apple product before i was thinking what could be the issue. after a while and old incident hit my mind, when one of my friend had issue with one USB drive which was not getting detected by any PC. that time it was rusty connector pins and cleaned them and it started working again.

So solution that really worked

1. Switch off the phone
2. Clean charging port of phone with needle (preferably wooden toothpick) clean all copper points inside.

3. Same way clean the cable USB port.

4. Take a pure cotton cloth and clean other side of connector.

5. take charger out of socket and cleat copper points where USB cable goes. (i didn’t tried but its better to do clean it)
After this process that iPhone started to charge normally and till date it is charging without any issue.
just in case even after completing these steps still your issue is not resolved.

Try following steps.

1.  carefully check cable is not broken or damaged (you can try to charge another iPhone using same cable to make it sure)
2. Connect charger to another wall socket , there might be little spark or shortage that is preventing accessory identification.
3. 1st connect cable with phone and then plug into power cord.

i hope by following above steps your issue will be rectified. because in my opinion dust & rust are the main culprit if your accessories are original.