How to implement Recursion in Swift

Posted on 29 Oct 2020 . 2 min read

In Computer Science, recursive function is a function that calls itself to solve problem and this technique is called recursion. Almost all programming languages support recursion and Swift programming language is one of them.

In this article, you will learn how to implement recursion in Swift programming language.

A recursive function can have one or more inputs to produce result and it must have base case to avoid calling itself infinitely. The first is a "base case" that breaks the recursion and the second case is a "recursive case". Let's see how we can implement recursion in Swift.

First of all, create function called recursive with one parameter input with type Int and it has return type of Int also.

func recursive(input: Int) -> Int { }

Now we will create "base case" for recursion. In base case, if input is less than or equals to 0 it will return input.

if input <= 0 {
    return input
}

Now it's time to implement "recursive case". In recursive case function will call itself.

else {
    return recursive(input: input - 1)
}

Final code


import UIKit
func recursive(input: Int) -> Int {
    print(input)
    if input <= 0 {
       return input
    } else {
       return recursive(input: input - 1)
    }
}
recursive(input: 4)

Output

Conclusion

In computer science, recursive approach can solve many problems and these problems can be solved by iteration. These are the basic fundamentals of computer science. Its always beneficial to know for interview purpose that how we can implement recursion.

Don’t hesitate to contact me if you have any questions or queries. Follow me on twitter @gurjitpt for any updates.

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Gurjit Singh

I’m Computer Science graduate and an iOS Engineer who writes about Swift and iOS development. Follow me for more updates:

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