Adapter Heating issue
i bought a 20watt adapter from this apple website and i found a issue that is my adapter and my phone facing overheating.im useing apple original cable btw
Presumably you refer to the Power Adapter used to charge your iPhone. It is entirely normal for the Power Adapter and/or the connected iPhone to become warm or very warm while charging.
The key point is that whilst either may become very warm in normal use, they should not become uncomfortably hot to handle. If your iPhone is becoming too hot to hold at any time, or the Power Adapter during charging, you should take them along to the Genius Bar at your local Apple Store - where the technicians can examine and test them for faults.