The code seems acceptable at first but has terrible performance after about 10 complex coloring brush strokes. I used this as a starting point for an app idea, but after working with it for months now trying to improve performance (and it's a deal breaker - you can't even zoom unless you deal with some major stutters) I will need to abandon this and go in another direction and/or write my own code that's actually efficient, from scratch. That may not be an option for most people, so I'm leaving this review here. Oleg is nice and does respond to e-mail requests but provided no help with the performance request as described here.

If you know Swift. This app is a great up to start with for color coding. Easy to customize. I am enjoying playing around the source code. There is much of improvements I had already did in my app. I did not have any idea how coloring books works but through this source code I have learned a lot. Though I had a challenge how to create the SVG file. I guarantee you it's pretty is. This is a good source frame work to start with. I managed to create my own app Called Colorants. If you want to check it my App https://apps.apple.com/us/app/colorants/id1526836928. Thank you for your support . Yes sometimes, I ask for the information that I was not familiar with. If you are someone wants to try it the price up there its worth it