What are some alternatives?
GIMP - GIMP is a multiplatform photo manipulation tool.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
Sketch - Professional digital design for Mac.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Affinity Designer - Professional creative software, exclusively for Mac.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.