i want to create functionality like interface in swift, my goal is when i call another class suppose i\'m calling API and the response of that class i want to reflect in to my c
Instead of interface swift have Protocols.
A protocol defines a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality. The protocol can then be adopted by a class, structure, or enumeration to provide an actual implementation of those requirements. Any type that satisfies the requirements of a protocol is said to conform to that protocol.
lets take an exam .
protocol Animal {
    func canSwim() -> Bool
}
and we have a class that confirm this protocol name Animal
class Human : Animal {
   func canSwim() -> Bool {
     return true
   }
}
for more go to - https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html
What are you finding is `Protocol'. Interfaces are same as protocol in Swift.
protocol Shape {
    func shapeName() -> String
}
class Circle: Shape {
    func shapeName() -> String {
        return "circle"
    }
}
class Triangle: Shape {
    func shapeName() -> String {
        return "triangle"
    }
}
class and struct both can implements the protocol.