Is LAMA something you use personally? I tried it out after seeing your post and deleted it in less time than it took to DL. Crashed repeatedly pretty much after every attempt to interact with it. Graphics choices made it pretty hard to assimilate data without a lot of concentration and the 'SPL' meter without calibration to a known external source that keeps its signal path gain fixed over time and many reconnects to the computer seems a stretch for non pro users. My preconcevied notions come from years of using SpectrFoo and Smaart and suffer accordingly but this app seems to be iOS happy. Just curious as how much luck you've had with it versus just knowing its on the shelf as it were.
For mac, have a look at LAMA (Little Audio Measurement App). It does do FFT measurements in addition to RTA style measurements.
Also, usefully for a church, it has a proper SPL meter and includes a built in HTTP server for monitoring sites remotely.
Its much cheaper than Smaart and very easy to use