How do I specify that a non-generic Swift type should comply to a protocol?

Question

I\'d like to implement a Swift method that takes in a certain class type, but only takes instances of those classes that comply to a specific protocol. For example, in Objec

Answer 1

From Swift 4 onwards you can do:

func addFilter(newFilter: GPUImageOutput & GPUImageInput)

Further reading: https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html

http://braking.github.io/require-conformance-to-multiple-protocols/

Multiple Type Constraints in Swift