Image & PDF annotation and saving it

We are looking for a Learning Management system for iOS, Android using Xamarin Forms. we are looking for help completing an image & PDF annotation feature, where the user draws on top of a captured picture and saves it as a new image with the annotations they've drawn on it. I have partially implemented this feature, but I am having trouble getting it to work. I will likely have many more projects involving image editing features, so I am hoping to find someone who will be able to do multiple projects for me.