C-182 Single Pilot reported an NMAC event during landing with another single engine aircraft in which both pilots took evasive action. C-182 Pilot was later informed they were on wrong radio frequency.

Narrative

Using Foreflight I identified the Tower and UNICOM frequencies; and believed since Tower was inoperative during my flight; the UNICOM frequency XXX.XX was what I should be relaying my pattern positions on. The aircraft ADSB In was inop and I was using a STRATUX linked to my IPAD for traffic awareness. I was operating with landing lights; nav lights; and strobe lights on. After not hearing radio communications on UNICOM ; I switched to Tower while I was approaching the pattern and made a call in the blind to Tower; XXX.XY. I received no reply and after listening for a bit; heard no other communications so switched back to UNICOM ; XXX.XX. I saw an aircraft on my iPad--stratux; looked like on final. However; I had been reporting my pattern position and had heard no one else reporting. I could not pick other aircraft up visually; but it looked like it might have been on a straight-in final. I turned left base; still not seeing the other aircraft; so I rolled out a bit and flattened my descent to stay above until I could pick up visually. During the rollout; I saw the other aircraft (believe a Cherokee); in a steep avoidance turn to my left and below. I was not sure it was an avoidance turn; so I started a climbing right hand turn to get above pattern altitude and get east of the field. I returned to pattern after noting the aircraft had landed. After landing the FBO operator came out and mentioned that I should have been on Tower frequency and that had seen a light on their receiver indicating someone was communicating on UNICOM . I understand now that C on a VFR sectional next to a frequency means that is the common traffic advisory frequency to use.