I had reports from my iOS users who installed iOS 12 that the degree symbol I use in graphics with the SkiaSharp.Extended plugin is broken and puts the square (character not found) in it's place. So I installed iOS 12 on my iPhone and found it true. It worked under the iOS 11 builds. I'm not sure whether I want to replace it with a colon or wait and see if Apple fixes it. Seems Apple likes to do whatever they want with fonts but that is a weird character to break.