SpiralKit is a Quartz 2D-based drawing framework for iOS written in Objective-C. The framework enables ‘drawing’ on a UIView in iOS and ships with pen, highlighter, and eraser drawing effects.

The framework is built specifically to enable adding new effects, color spaces, and drawing algorithms in a modular fashion. If you want to provide a unique drawing effect, support of the CMYK color space, or a custom drawing algorithm, you can add such features to SpiralKit without having to modify the fundamental components of the framework in most cases.

If you’re looking for a solution for incorporating drawing functionality into an iOS project, download SpiralKit and see if it fits your needs. The framework is released as Open Source Software under the Apache 2.0 License and can be used free of charge.

Where to Find It

The project is hosted on GitHub at https://github.com/digital-generalists/spiralkit.

Inspiration for the Framework

We believe in the value of Open Source Software and want to contribute to the community whenever it makes sense to do so. We believe that by releasing Spiral’s drawing engine, we can help developers build amazing features into their products. Additionally, our collective hope is that we’ll learn as much from the developers who adopt SpiralKit as they do from the project.


The original implementation of SpiralKit was influenced by this post. The final implementation is deeply spiked from the one provided in that article, but we want to give credit for the initial direction.

The Douglas-Peucker algorithm implementation methods in this framework are based on work from https://github.com/andreac/lineSmooth.