Swift Tutorial - Tutorialspoint

let student = Person(name: "Roshan", age: 19 )

print(student)

When we run the above program using playground, we get the following result:

Priya is 21 years old

Rehan is 29 years old

Roshan is 19 years old

Checking for Protocol Conformance

Protocol conformance is tested by 'is' and 'as' operators similar to that of type casting.

 The is operator returns true if an instance conforms to protocol standard and

returns false if it fails.

 The as? version of the downcast operator returns an optional value of the

protocol's type, and this value is nil if the instance does not conform to that

protocol.

 The as version of the downcast operator forces the downcast to the protocol type

and triggers a runtime error if the downcast does not succeed.

import Foundation

@objc protocol rectangle {

var area: Double { get }

}

@objc class Circle: rectangle {

let pi = 3.1415927

var radius: Double

var area: Double { return pi * radius * radius }

init(radius: Double) { self.radius = radius }

}

@objc class result: rectangle {

var area: Double

init(area: Double) { self.area = area }

}