Yes. I have Pocket Light Meter by Nuwaste Studios (most used). Lightmate is comparable. The app Lightme should be very good but I find it very confusing and grab to Pocket Light Meter 9 times out of 10.Point the iphone camera at something 18% grey (grass, tiles or asphalt) in the shade and consider the rest as sunny 16 (clouds entering, +1, sun brighter -1, etc).

Just use your lightmeter and app simultaniously at home fooling around and you’ll quickly learn when it needs adjustment and with what it is most reliable.