Protocol Oriented Programming in Swift

Protocol-Oriented Programming (POP) is a design pattern that is becoming increasingly popular among advanced Swift developers. POP is a style of programming that emphasizes the use of protocols to provide a more flexible and modular code structure. By utilizing protocols, we can create code that can be easily extended, tested and reused. A protocol is a type which defines an interface that other types can conform to. Protocols can be used to specify a set of methods and properties that a conforming class, struct or enum must implement. A protocol can be adopted by a class, struct or enum to provide a specific functionality or behavior. Let's see an example of how we can define and use a protocol in Swift.

protocol Calculator {
    var operand1: Double { get set }
    var operand2: Double { get set }
    
    func add() -> Double
    func subtract() -> Double
    func multiply() -> Double
    func divide() -> Double
}

struct BasicCalculator: Calculator {
    var operand1: Double
    var operand2: Double
    
    func add() -> Double {
        return operand1 + operand2
    }
    func subtract() -> Double {
        return operand1 - operand2
    }
    func multiply() -> Double {
        return operand1 * operand2
    }
    func divide() -> Double {
        if operand2 == 0 {
            return 0
        }
        return operand1 / operand2
    }
}

let basicCalc = BasicCalculator(operand1: 5, operand2: 2)
print(basicCalc.add())      //Output: 7.0
print(basicCalc.subtract()) //Output: 3.0
print(basicCalc.multiply()) //Output: 10.0
print(basicCalc.divide())   //Output: 2.5}

In this example, we have created a protocol named `Calculator` with four methods: `add()`, `subtract()`, `multiply()` and `divide()`. The `BasicCalculator` struct implements all methods of the `Calculator` protocol. Now, we can easily create new calculators by creating new structs or classes that adopt the `Calculator` protocol. For example, we can create a scientific calculator as follows:

struct ScientificCalculator: Calculator {
    var operand1: Double
    var operand2: Double
    
    func add() -> Double {
        return operand1 + operand2
    }
    func subtract() -> Double {
        return operand1 - operand2
    }
    func multiply() -> Double {
        return operand1 * operand2
    }
    func divide() -> Double {
        if operand2 == 0 {
            return 0
        }
        return operand1 / operand2
    }
    
    func sin() -> Double {
        return sin(operand1)
    }
    
    func cos() -> Double {
        return cos(operand1)
    }
    
    func tan() -> Double {
        return tan(operand1)
    }
}

let scientificCalc = ScientificCalculator(operand1: Double.pi/2, operand2: 2)
print(scientificCalc.sin()) //Output: 1.0
print(scientificCalc.cos()) //Output: 0.0
print(scientificCalc.tan()) //Output: Inf}

In the example above, the `ScientificCalculator` struct also implements the `sin()`, `cos()` and `tan()` methods, which are not part of the `Calculator` protocol. This is the power of protocol-oriented programming – creating modular and flexible code that can be easily extended and reused. Summary: Protocol-Oriented Programming is a design pattern that emphasizes the use of protocols to provide a more flexible and modular code structure. By utilizing protocols, we can create code that can be easily extended, tested, and reused. In this tutorial, we saw an example of how we can define and use a protocol in Swift.

Protocol Oriented Programming in Swift

by The Captain

Protocol Oriented Programming in Swift