Section 1.1: The Purpose of Generics

Consider a scenario where you need to implement a function to print information about an argument of any type, such as a String or an Int. Without generics, you'd have to define multiple functions for each possible data type:

func infoString(_ a: String) {

print("Argument type is String with a value of (a)")

}

func infoInt(_ a: Int) {

print("Argument type is Int with a value of (a)")

}

func infoDouble(_ a: Double) {

print("Argument type is Double with a value of (a)")

}

// ... and so on

This approach leads to excessive repetition and is impractical given the myriad of data types available.

Instead, generics allow you to create a single function that can accept any type:

func info<T>(_ a: T) {

print("Argument type is (type(of: a)) with a value of (a)")

}

Now, you can use this function for various types of inputs:

info(3) // Argument type is Int with a value of 3

info(3.2) // Argument type is Double with a value of 3.2

info("Yeah") // Argument type is String with a value of Yeah

This implementation utilizes a generic placeholder type T, indicating that the function can accept any type. Including <T> after the function name signifies the use of this placeholder.

Section 1.2: Another Use Case for Generics

Imagine you have arrays containing different types, such as integers or strings, and you want to print their contents. With separate functions for each type, the code becomes redundant:

let numbers = [1, 2, 3, 4, 5]

let names = ["Nicolas", "Anne", "Robert", "Sofie"]

func printInts(_ arr: [Int]) {

arr.forEach { print($0) }

}

func printStrings(_ arr: [String]) {

arr.forEach { print($0) }

}

printInts(numbers) // prints all the numbers

printStrings(names) // prints all the names

Instead of duplicating functions, a generic printing function can be utilized:

func arrPrint<T>(_ arr: [T]) {

arr.forEach { print($0) }

}

You can now easily print both arrays:

arrPrint(numbers) // prints all the numbers

arrPrint(names) // prints all the names