The Dark Sky Meter app measures the sky brightness and shares it (optionally) with scientists around the globe.
iOS 12 support
Ratings and Reviews
Love this app
This app along with info on their web site is a real boon. In my experience it is quite accurate and useful in comparing observing sites. However it appears it saves only your most recent recordings which is too bad. Also until just recently it has a second benefit of reporting local predicted seeing and transparency as now I cannot get it to report. It has been a great app! I very much hope it is not on its way out. Get this app and support a very useful tool!
Measure the Night Dky
Dark Sky Meter is the first app for iPhone to allow users to accurately measure the brightness of the night sky. Amateur astronomers and dark sky advocates are likely familiar with the Sky Quality Meter (SQM) device. This app gives you an SQM in your phone and for the 4S and 5 gives very accurate results without having to buy an SQM. The app is well worth the purchase price.
Works great on iPhone5s (not on 6 though)
I've had good results with this on my iPhone5s. The results seem relatively reliable and consistent with dedicated SQM meters. Definitely well worth the price!
However, many members of my astronomy club have tried this on their iPhone6/6 Plus and are finding the results are very inconsistent and completely useless.
With Family Sharing set up, up to six family members can use this app.