I wrote a 2-part series on GamePlayKit’s Rule Systems framework for Smashing Magazine.
Part 1 is the basic idea and shows how to replace conditional logic that might be strewn around a project into a GamePlayKit rule-system.
In Part 2, I show the support for fuzzy logic rule-systems (logic values ranging from 0.0 to 1.0 instead of strictly true and false). It covers a little more of the features of rule-systems and how to implement NOT, OR, and AND for fuzzy values.
Both articles are supported by Swift Playgrounds in GitHub so that you can play with the concept and try different rules.