Solid In Swift

Same Responsibility Principle - Each entity should have only one responsibility (Granular Classes)
Open / Close Principle - Entities should be Open For Extension Close for Modifications { If you have to modify another class each time you add expected behavior }
Liskov Substitution Principle - Subclasses should not break the expectations of the parent class. You don't have to know the concrete type of a (sub) class to know it behaves in an expected way.
Interface Segregation Principle - Instead of one monolithic interface, break an interface up based on what implementers should be doing. Keeps consumers from having too much Power
Dependency Inversion Principle - High-level modules should not know the details of low-level modules.

Solid in Swift
https://github.com/prolificinteractive/SOLID-Principles