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30 seconds of swift code

A Swift implementation of 30-seconds-of-code: A curated collection of useful Swift 4 snippets that you can understand in 30 seconds or less.

From elizabethsiegle·Updated April 5, 2026·View on GitHub·

>A Swift implementation of 30-seconds-of-code: A curated collection of useful Swift 4 snippets that you can understand in 30 seconds or less. * Use Ctrl + F or command + F to search for a snippet. The project is written primarily in Swift, first published in 2018. Key topics include: 30-seconds-of-code, awesome, awesome-list, collection, education.

30-seconds-of-swift-code Tweet

first-timers-onlyPRs Welcome

Welcome to 30-seconds-of-swift-code!

A Swift implementation of 30-seconds-of-code: A curated collection of useful Swift 4 snippets that you can understand in 30 seconds or less.

  • Use <kbd>Ctrl</kbd> + <kbd>F</kbd> or <kbd>command</kbd> + <kbd>F</kbd> to search for a snippet.

Note:- This is in no way affiliated with the original 30-seconds-of-code.

If you've come here from JavaScript land then you should be aware that this project uses Swift 4, therefore not all snippets will work as expected on every system. You'll need to check your Swift version by going to Project and then following the steps below.
<br />
<br />
version

If you need help installing the latest stable release of Swift 4 check out swift.org. If you run into trouble make sure you check out Stackoverflow.

This project contains plenty of useful snippets which can help beginners and newcomers quickly ramp-up their skills on Swift 4.

Table of contents

:books: List

<details><summary>View contents</summary> <ul><li><a href = "#bubble-sort"><code>bubbleSort</code></a></li> <li><a href = "#filter-bools"><code>filterBools</code></a></li> <li><a href = "#chunk"><code>chunk</code></a></li> <li><a href = "#count-occurrences"><code>countOccurrences</code></a></li> <li><a href = "#deep-flatten"><code>deepFlatten</code></a></li> <li><a href = "#difference"><code>difference</code></a></li> <li><a href = "#duplicates"><code>duplicates</code></a></li> <li><a href = "#every_nth"><code>every_nth</code></a></li> <li><a href = "#insertion-sort"><code>insertionSort</code></a></li> <li><a href = "#fisher-yates-shuffle"><code>fisherYatesShuffle</code></a></li> <li><a href = "#calc-median"><code>calcMedian</code></a></li> <li><a href = "#calc-better-median"><code>calcBetterMedian</code></a></li> <li><a href = "#average"><code>average</code></a></li> <li><a href = "#factorial"><code>factorial</code></a></li> <li><a href = "#gcd"><code>gcd</code></a></li> <li><a href = "#lcm1"><code>lcm1</code></a></li> <li><a href = "#lcm2"><code>lcm2</code></a></li> <li><a href = "#maxn"><code>maxn</code></a></li> <li><a href = "#minn"><code>minn</code></a></li> <li><a href = "#all-unique"><code>allUnique</code></a></li> <li><a href = "#just-keys"><code>justKeys</code></a></li> <li><a href = "#just-values"><code>justValues</code></a></li> <li><a href = "#bytes-from-string"><code>bytesFromString</code></a></li> <li><a href = "#capitalize-first"><code>capitalizeFirst</code></a></li> <li><a href = "#capitalize-every-word"><code>capitalizeEveryWord</code></a></li> <li><a href = "#count-vowels"><code>countVowels</code></a></li> <li><a href = "#lower-case-first-letter-of-first-word"><code>lowerCaseFirstLetterOfFirstWord</code></a></li> <li><a href = "#is-lower-case"><code>isLowerCase</code></a></li> <li><a href = "#is-upper-case"><code>isUpperCase</code></a></li> <li><a href = "#palindrome"><code>palindrome</code></a></li> <li><a href = "#anagram"><code>anagram</code></a></li> <li><a href = "#drop"><code>drop</code></a></li> <li><a href = "#drop-right-while"><code>dropRightWhile</code></a></li> <li><a href = "#nth-element"><code>nthElement</code></a></li> <li><a href = "#filter-non-unique"><code>filterNonUnique</code></a></li> <li><a href = "#generic-flatten"><code>genericFlatten</code></a></li> <li><a href = "#comma-separated"><code>commaSeparated</code></a></li> <li><a href = "#most-frequent"><code>mostFrequent</code></a></li> <li><a href = "#byte-size"><code>repeating</code></a></li> </ul></details>

:heavy_division_sign: Math

<details><summary>View contents</summary> <ul><li><a href = "#average"><code>average</code></a></li> <li><a href = "#gcd"><code>gcd</code></a></li> <li><a href = "#lcm1"><code>lcm1</code></a></li> <li><a href = "#lcm2"><code>lcm2</code></a></li> <li><a href = "#maxnn"><code>maxn</code></a></li> <li><a href = "#minnn"><code>minn</code></a></li> <li><a href = "#factorial"><code>factorial</code></a></li> <li><a href = "#calc-median"><code>calcMedian</code></a></li> <li><a href = "#calc-better-median"><code>calcBetterMedian</code></a></li> <li><a href = "#radians-to-degrees"><code>radiansToDegrees</code></a></li> </ul></details>

:card_file_box: Object

<details><summary>View contents</summary> <ul><li><a href = "#all-unique"><code>allUnique</code></a></li> <li><a href = "#just-keys"><code>justKeys</code></a></li> <li><a href = "#just-values"><code>justValues</code></a></li> </ul></details>

:scroll: String

<details><summary>View contents</summary> <ul> <li><a href = "#bytes-from-string"><code>bytesFromString</code></a></li> <li><a href = "#capitalize-first"><code>capitalizeFirst</code></a></li> <li><a href = "#capitalize-everyword"><code>capitalizeEveryWord</code></a></li> <li><a href = "#count-vowels"><code>countVowels</code></a></li> <li><a href = "#lower-case-first-letter-of-first-word"><code>lowerCaseFirstLetterOfFirstWord</code></a></li> <li><a href = "#is-lower-case"><code>isLowerCase</code></a></li> <li><a href = "#is-upper-case"><code>isUpperCase</code></a></li> <li><a href = "#palindrome"><code>palindrome</code></a></li> <li><a href = "#snake"><code>snake</code></a></li> <li><a href = "#simple_snake_case"><code>simple_snake_case</code></a></li> <li><a href = "#first-unique-character"><code>firstUniqueCharacter</code></a></li> <li><a href = "#repeating"><code>repeating</code></a></li> <li><a href = "#byte-size"><code>repeating</code></a></li> </ul></details> <hr></hr>

:books: List

bubble sort

BubbleSort is a sorting algorithm that uses the technique of repeatedly comparing and swapping the adjacent elements if they are in the wrong order.

swift
func bubbleSort(_ inputArr:[Int]) -> [Int] {
    guard inputArr.count > 1 else {
        return inputArr
    }
    var res = inputArr
    let count = res.count
    var isSwapped = false
    repeat {
        isSwapped = false
        for index in stride(from: 1, to: count, by: 1) {
            if res[index] < res[index - 1] {
                res.swapAt((index - 1), index)
                isSwapped = true
            }
        }
    } while isSwapped
    return res
}
<details><summary>View Examples</summary> 
swift
bubbleSort([32,12,12,23,11,19,81,76]) //[11, 12, 12, 19, 23, 32, 76, 81]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

chunk

Chunks an array into smaller arrays of a certain size.

swift
func chunk(arr: [Any], chunkSize: Int) -> [Any] {
    let chunks = stride(from: 0, to: arr.count, by: chunkSize).map {
        Array(arr[$0..<min($0 + chunkSize, arr.count)])
    }
    return chunks
}
<details><summary>View Examples</summary> 
swift
chunk(arr: [2, 4, 6, 8], chunkSize: 1) //[[2], [4], [6], [8]]
chunk(arr: [1, 3, 5, 9], chunkSize: 4) //[[1, 3, 5, 9]]
chunk(arr: ["hi", "yo", "bye", "bai"], chunkSize: 3) //[["hi", "yo", "bye"], ["bai"]]
chunk(arr: ["young", "scrappy", "hungry"], chunkSize: 2) //[["young", "scrappy"], ["hungry"]]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

every_nth

Returns every nth element in a given list and a new list is created that contains every nth element of the given list.

swift
func getEvery( nth: Int, from list: [Any] ) {
    var nthElements = [Any]()
    var shiftedList = list
    shiftedList.insert(0, at: 0)
    
    for (i, element) in shiftedList.enumerated() {
        if i > 0 && i.isMultiple(of: nth) {
            nthElements.append(element)
        }
    }
}
<details><summary>View Examples</summary> 
swift
getEvery(nth: 4, from: ["The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog"])  //["fox", "lazy"]

getEvery(nth: 2, from: [1,2,3,4,5,6,7,8,9]) //[2, 4, 6, 8]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

filter bools

Remove every value that's not a Boolean.

swift
func filterBools(_ inputArr: [Any]) -> [Any] {
    return inputArr.compactMap { $0 as? Bool }
    
}
<details><summary>View Examples</summary> 
swift
filterBools([false, 2, "lol", 3, "a", "s", 34, false, true]) //[false, false, true]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

count occurrences

Count occurrences of a string in an array.

swift
func countOccurrences(arr: [String], into: String) -> Int {
    return arr.reduce(0) { $1 == into ? $0 + 1 : $0 }
}
<details><summary>View Examples</summary> 
swift
countOccurrences(arr: ["FOO", "FOO", "BAR"], into: "FOO") //2
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

deep flatten

Deep flattens a list with recursion.

swift
func deepFlatten(arr: [AnyHashable]) -> [AnyHashable] {
    var arr2 = [AnyHashable]()
    for el in arr {
        if let el = el as? Int {
            arr2.append(el)
        }
        if let el = el as? [Any] {
            let res = deepFlatten(arr: el as! [AnyHashable])
            for i in res {
                arr2.append(i)
            }
        }
    }
    return arr2
}
<details><summary>View Examples</summary> 
swift
deepFlatten(arr: [6, 5, 4, [3, 2], [1]]) //[6, 5, 4, 3, 2, 1]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

difference

Return element(s) not contained in both of the given arrays (ie. elements only contained in one array and not both.)

swift
func difference(arr1: [AnyHashable], arr2: [AnyHashable]) -> Set<AnyHashable> {
    return Set(arr1).symmetricDifference(arr2)
}
<details><summary>View Examples</summary> 
swift
difference(arr1: [2, 4, 6, 8], arr2: [10, 8, 6, 4, 2, 0]) //10
difference(arr1: ["mulan", "moana", "belle", "elsa"], arr2: ["mulan", "moana", "belle", "pocahontas"]) //elsa, pocahontas
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

duplicates

Check for duplicate elements in a given array.

swift
func duplicates(arr1: [AnyHashable]) -> Bool {
    return arr1.count != (Set<AnyHashable>(arr1)).count
}
<details><summary>View Examples</summary> 
swift
duplicates(arr1: [5, 4, 3, 2]) //false
duplicates(arr1: ["hermione", "hermione", "ron", "harry"]) //true
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

insertion sort

Insertion Sort algorithm--inspired by Ray Wenderlich https://github.com/raywenderlich/swift-algorithm-club/tree/master/Insertion%20Sort.

swift
func insertionSort(_ array: [Int]) -> [Int] {
    var a = array             // 1
    for index in stride(from: 1, to: a.count, by: 1)  {
        var y = index
        while y > 0 && a[y] < a[y - 1] { // 3
            a.swapAt(y - 1, y)
            y -= 1
        }
    }
    return a
}
<details><summary>View Examples</summary> 
swift
let list = [ 10, -1, 3, 9, 2, 27, 8, 5, 1, 3, 0, 26 ]
insertionSort(list) //[-1, 0, 1, 2, 3, 3, 5, 8, 9, 10, 26, 27]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

Swift Standard Library Sort

Link to Official Apple Developer Documentation - https://developer.apple.com/documentation/swift/array/1688499-sort

swift
var integerArray = [5,8,2,3,656,9,1]
var stringArray = ["India", "Norway", "France", "Canada", "Italy"]
integerArray.sort() //[1, 2, 3, 5, 8, 9, 656]
stringArray.sort() //["Canada", "France", "India", "Italy", "Norway"]
<details><summary>View Examples</summary> 
swift
integerArray.sort() //[1, 2, 3, 5, 8, 9, 656]
stringArray.sort() //["Canada", "France", "India", "Italy", "Norway"]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

fisher yates shuffle

Fisher-Yates algorithm aka Knuth shuffle to shuffle an array creates a uniform shuffle of the array where each permutation is equally likely in O(n) time.

swift
func shuffle(arr1: [AnyHashable]) -> [AnyHashable] {
    var arr2 = arr1
    for i in stride(from: arr1.count - 1, through: 1, by: -1) {
        let j = Int.random(in: 0...i)
        if i != j {
            arr2.swapAt(i, j)
        }
    }
    return arr2
}
<details><summary>View Examples</summary> 
swift
var foo = [1,2,3]
shuffle(arr1: foo) //[2,3,1] , foo = [1,2,3]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

generic flatten

Takes an array of arrays as input and transforms it to a flattened array of its type. ( handles optionals )

swift
/// We use flat map to flatten the array and compact map to handle optionals
/// - Parameter arrays: Array of arrays to flatten
func flatten<T>(arrays: [[T?]]) -> [T] {
    return arrays.flatMap{$0}.compactMap{$0}
}
<details><summary>View Examples</summary> 
swift
flatten(arrays: [["a","b","c","d"],["e","f","g","y"]]) // ["a", "b", "c", "d", "e", "f", "g", "y"]
flatten(arrays: [[1,nil,3,4],[5,6,7,8]]) // [1, 3, 4, 5, 6, 7, 8]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

comma separated

Takes an array of strings and returns a single string with each element from the input list separated by commas.

swift
/// Return the elements of `strings` separated by ", "
func commaSeparated(_ strings: [String]) -> String {
    return strings.joined(separator: ", ")
}
<details><summary>View Examples</summary> 
swift
let strs = ["Foo", "Bar", "Baz", "Qux"]
commaSeparated(strs) // "Foo, Bar, Baz, Qux"
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

most frequent

Takes an array and returns the most frequent element that appears in the array.
The type of elements in the array must conform hashable.

swift
// Return the most frequent element that appears in the array
func mostFrequent<Type: Hashable>(_ arr: [Type]) -> Type? {
    var dict = [Type: Int]()
    for element in arr {
        if dict[element] == nil {
            dict[element] = 1
        } else {
            dict[element]! += 1
        }
    }
    return dict.sorted(by: { $0.1 > $1.1 }).first?.key
}
<details><summary>View Examples</summary> 
swift
mostFrequent([1, 2, 5, 4, 1, 9, 8, 7, 4, 5, 1, 5, 1]) // 1
mostFrequent(["a", "b", "c", "a"]) // "a"
mostFrequent([]) // nil
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

:heavy_division_sign: Math

average

Returns the average of two or more doubles in an array.

swift
func average(arr: [Double]) -> Double {
    return arr.reduce(0, +)/Double(arr.count)
}
<details><summary>View Examples</summary> 
swift
average(arr: [5, 4, 3, 2, 1]) //3
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

factorial

Calculates the factorial of a number.

swift
func factorial(num: Int) -> Int {
    var fact: Int = 1
    for index in stride(from: 1, to: num+1, by: 1) {
        fact = fact * index
    }
    return fact
}
<details><summary>View Examples</summary> 
swift
factorial(num: 4) //24
factorial(num: 10) //3628800
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

gcd

Calculates the greatest common divisor between two integers with recursion.

swift
func gcd(num1: Int, num2: Int) -> Int {
    let mod = num1 % num2
    if mod != 0 {
        return gcd(num1: num2, num2: mod)
    }
    return num2
}
<details><summary>View Examples</summary> 
swift
gcd(num1: 228, num2: 36) //12
gcd(num1: -5, num2: -10)
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

lcm1

Returns the least common multiple of two integers using the gcd function above.

swift
func lcm1(num1: Int, num2: Int) -> Int {
    return abs(num1 * num2) / gcd(num1: num1, num2: num2)
}
<details><summary>View Examples</summary> 
swift
lcm1(num1: 12, num2: 7) //84
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

lcm2

Least common multiple of an array using the first lcm.

swift
func lcm2(arr1: [Int]) -> Int {
    return arr1.reduce(1) { lcm1(num1: $0, num2: $1) }
}
<details><summary>View Examples</summary> 
swift
lcm2(arr1: [4, 3, 2]) //12
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

max n

Returns the maximum element from the provided array.

swift
func maxn(arr1: [Int]) -> Int {
    if let (_, maxValue) = arr1.enumerated().max(by: { $0.element < $1.element }) {
        return maxValue
    }
    return 0
}
<details><summary>View Examples</summary> 
swift
maxn(arr1: [2, 9, 5]) //9
[2, 9, 5].max() //9
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

min n

Returns the minimum integer from an array without the built-in .min() function (used in examples to compare results.)

swift
func minn(arr1: [Int]) -> Int {
    var minVal = arr1[0]
    for num in arr1 {
        minVal = (num  < minVal) ? num : minVal
    }
    return minVal
}
<details><summary>View Examples</summary> 
swift
minn(arr1: [8, 2, 4, 6]) //2
[8, 2, 4, 6].min() //2
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

calc median

One way of calculating the median of an array of integers.

swift
func calcMedian(arr: [Int]) -> Float {
    return Float(arr.sorted(by: <)[arr.count / 2])
}
<details><summary>View Examples</summary> ```swift calcMedian(arr: [1,2,3,4,5,6,7,8]) //returns 4.5 ``` </details> <br><a href = "#table-of-contents">:arrow_up: Back to top</a>

calc better median

Better way of calculating the median of an array of integers.

swift
func calcBetterMedian(arr: [Int]) -> Float {
    let sorted = arr.sorted()
    if sorted.count % 2 == 0 {
        return Float((sorted[(sorted.count / 2)] + sorted[(sorted.count / 2) - 1])) / 2
    }
    return Float(sorted[(sorted.count - 1) / 2])
}
<details><summary>View Examples</summary> 
swift
calcBetterMedian(arr: [1,2,3,4,5,6,7,8]) //returns 4.5
</details>

radians to degrees

Convert an angle from radians to degrees.

swift
func radiansToDegrees(_ angle: Double) -> Double {
    return angle * 180 / .pi
}
<details><summary>View Examples</summary> 
swift
radiansToDegrees(4) // 229.183
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

:card_file_box: Object

all unique

Checks a flat list for all unique values, returning True if list values are all unique and False if list values aren't all unique.

swift
func allUnique(arr: [AnyHashable]) -> Bool {
    return arr.count == Set<AnyHashable>(arr).count
}
<details><summary>View Examples</summary> 
swift
allUnique(arr: [5, 4, 3, 2]) //true
allUnique(arr: ["lol", "rofl", "lol"]) //false
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

just keys

Function which accepts a dictionary of key-value pairs and returns a new array of just the keys.

swift
func justKeys(dict: Dictionary<AnyHashable, AnyHashable>) -> [AnyHashable] {
    return Array(dict.keys)
}
<details><summary>View Examples</summary> 
swift
var dict: Dictionary<String, String> = ["Mulan": "Mushu", "Anna": "Olaf", "Pocahontas": "Fleeko"]
justKeys(dict: dict) //[Anna, Mulan, Pocahontas]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

just values

Function which accepts a dictionary of key-value pairs and returns a new array of just the values.

swift
func justValues(dict: Dictionary<AnyHashable, AnyHashable>) -> [AnyHashable] {
    return Array(dict.values)
}
<details><summary>View Examples</summary> 
swift
justValues(dict: dict) //[Olaf, Mushu, Fleeko]
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

:scroll: String

bytes from string

Get bytes of a string.

swift
func bytes(_ str: String) -> Int {
    return str.utf8.count
}
<details><summary>View Examples</summary> 
bytes("Hello")
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

capitalize first

Capitalizes the first letter of a string, leaving the rest the same.

swift
func capitalizeFirst(str: String) -> String {
    var components = str.components(separatedBy: " ")
    components[0] = components[0].capitalized
    return components.joined(separator: " ")
}
<details><summary>View Examples</summary> 
capitalizeFirst(str: "i like cheesE") //I like cheesE
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

capitalize every word

Capitalizes the first letter of every word in a string.

swift
func capitalizeEveryWord(str: String) -> String {
    return str.capitalized
}
<details><summary>View Examples</summary> 
swift
capitalizeEveryWord(str: "on a scale from 1 to 10 how would you rate your pain") //On A Scale From...
capitalizeEveryWord(str: "well, hello there!") //Well, Hello There!
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

count vowels

Retuns number of vowels in provided string.

swift
func countVowels(str: String) -> Int {
    var vowelCount = 0
    let vowels = Set(["a", "e", "i", "o", "u"])
    for char in str.lowercased() {
        if vowels.contains("\(char)") {
            vowelCount += 1
        }
    }
    return vowelCount
}
<details><summary>View Examples</summary> 
swift
countVowels(str: "hi mom") //2
countVowels(str: "aeiou") //5
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

lower case first letter of first word

Decapitalizes the first letter of the first word in a string.

swift
func lowerCaseFirstLetterOfFirstWord(str: String) -> String {
    var components = str.components(separatedBy: " ")
    components[0] = components[0].lowercased()
    return components.joined(separator: " ")
}
<details><summary>View Examples</summary> 
swift
lowerCaseFirstLetterOfFirstWord(str: "Christmas Switch was a solid movie") //christmas Switch...
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

is lower case

Return true if any character in a string is capitalized.

swift
func isLowerCase(str: String) -> Bool {
    return str == str.lowercased()
}
<details><summary>View Examples</summary> 
swift
isLowerCase(str: "I LOVE CHRISTMAS") //false
isLowerCase(str: "<3 lol") //true
</details>

<br><a href = "#table-of-contents">:arrow_up: Back to top</a>

is upper case

Checks that each character in a string is uppercase.

swift
func isUpperCase(str: String) -> Bool {
    return str == str.uppercased()
}
<details><summary>View Examples</summary> 
swift
isUpperCase(str: "LOLOLOL") //true
isUpperCase(str: "lmao") //false
isUpperCase(str: "Rofl") //false
</details>

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palindrome

Returns True if the given string is a palindrome, False if otherwise.

swift
func palindrome(str: String) -> Bool {
    return str.lowercased() == String(str.reversed()).lowercased()
}
<details><summary>View Examples</summary> 
swift
palindrome(str: "racecar") //true
palindrome(str: "Madam") //true
palindrome(str: "lizzie") //false
</details>

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anagram

Returns True if the 2 given strings are perfect anagrams of each other, False if otherwise.

swift
/// Return `true` if the 2 given strings are "perfect" anagrams.
/// (they consist of the same characters excluding whitespace)
func anagram(_ str1: String, _ str2: String) -> Bool {
    let s1 = str1.filter { !$0.isWhitespace }.lowercased()
    let s2 = str2.filter { !$0.isWhitespace }.lowercased()
    return s1.count == s2.count && s1.sorted() == s2.sorted()
}
<details><summary>View Examples</summary> 
swift
anagram("abcd3", "3acdb") // true
anagram("123", "456") // false
anagram("Buckethead", "Death Cube K") // true
</details>

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drop

Returns a new array with n elements removed from the left.

swift
func drop(arr: [AnyHashable], num: Int) -> [AnyHashable] {
    return Array(arr.dropFirst(num)) //need Array() to concert ArraySlice to Array
}
<details><summary>View Examples</summary> 
swift
drop(arr: [5, 4, 3, 2, 1, 0], num: 1)
drop(arr: ["Huey", "Dewey", "Louie"], num: 3)
</details>

array to csv

Returns a CSV-String created from 2D-Array.

swift
func arrayToCSV(_ inputArray: [Array<String>]) -> String {
    var csv: String = ""
    for row in inputArray {
        csv.append(row.map { "\"\($0)\"" } .joined(separator: ", ") + "\n")
    }
    return csv
}
<details><summary>View Examples</summary> 
swift
arrayToCSV([["a", "b", "c"], ["d", "e", "f"], ["g", "h", "i"]])
//"a", "b", "c"
//"d", "e", "f"
//"g", "h", "i"
</details>

flip

Returns the given function with fliped arguments.

swift
func flip<A, B, C>(_ function: @escaping ((A, B) -> C)) -> ((B, A)->C) {
    return { (a, b) in
        return function(b, a)
    }
}
<details><summary>View Examples</summary> 
swift
// flip example 1
func concat(_ alpha: String, _ beta: String) -> String {
    return alpha + beta
}

let reverseConcat = flip(concat)
concat("A", "B") //"AB"
reverseConcat("A", "B") //"BA"

// flip example 2
func gt(_ a: Int, _ b: Int) -> Bool {
    return a > b
}

let lt = flip(gt)

gt(5, 3) //true
lt(5, 3) //false
gt(2, 5) //false
lt(2, 5) //true
</details>

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drop right while

Removes elements from the end of an array until the passed function returns true.

swift
func dropRight(arr: [Int], while predicate: ((Int) -> Bool)) -> [Int] {
    var returnArr = arr
    for item in arr.reversed() {
        if predicate(item) { break }
        returnArr = returnArr.dropLast()
    }
    return returnArr
}
<details><summary>View Examples</summary> 
swift
dropRight(arr: [1, 2, 3, 4, 5], while: { $0 < 0 }) //[]
dropRight(arr: [1, 2, 3, 4, 5], while: { $0 > 0 }) //[1, 2, 3, 4, 5]
</details>

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filter non unique

Filters out the non-unique values in a list

swift
func filterNonUnique(arr: [Any]) -> [Any] {
    let set = NSOrderedSet(array: arr)
    return set.array
}
<details><summary>View Examples</summary> 
swift
filterNonUnique(arr: [1, 2, 2, 3, 5]) // [1, 2, 3, 5]
filterNonUnique(arr: ["Tim", "Steve", "Tim", "Jony", "Phil"]) // ["Tim", "Steve", "Jony", "Phil"]
</details>

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snake

Returns a new string in snake case

swift
func snake(str: String) -> String? {
    let pattern = "([a-z0-9])([A-Z])"

    let regex = try? NSRegularExpression(pattern: pattern, options: [])
    let range = NSRange(location: 0, length: str.count)
    return regex?.stringByReplacingMatches(in: str, options: [], range: range, withTemplate: "$1_$2")
        .lowercased() 
        .replacingOccurrences(of: " ", with: "_")
        .replacingOccurrences(of: "-", with: "_")
}
<details><summary>View Examples</summary> 
swift
snake(str: "camelCase") // 'camel_case'
snake(str: "some text") // 'some_text'
snake(str: "some-mixed_string With spaces_underscores-and-hyphens") // 'some_mixed_string_with_spaces_underscores_and_hyphens'
snake(str: "AllThe-small Things") // "all_the_smal_things"
</details>

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simple_snake_case

Returns a new string in snake case

swift
func snakeCase(_ string: String) -> String {
    let arrayOfStrings = text.components(separatedBy: " ")
    return arrayOfStrings.joined(separator: "_")
}
<details><summary>View Examples</summary> 
swift
    let text = "Snake case is the practice of writing compound words or phrases in which the elements are separated with one underscore character and no spaces."
    snakeCase(text)
</details>

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first-unique-character

Returns first unique character in a string

swift
func firstUniqueCharacter(_ str: String) -> Character? {
  var countDict: [Character: Int] = [:]
  for char in str {
    countDict[char] = (countDict[char] ?? 0) + 1
  }
  return str.filter{countDict[$0] == 1}.first
}
<details><summary>View Examples</summary> 
swift
firstUniqueCharacter("barbeque nation") //"r"
</details>

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repeating

Prints a string N times without using loops.

swift
func repeating(_ repeatedValue: String, count: Int) {
    guard count > 0 else {
        return
    }
    
    print(repeatedValue)
    
    repeating(repeatedValue, count: count - 1)
}
<details><summary>View Examples</summary> 
swift
repeating("Text", count: 5)
</details>

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byte-size

Returns length of string in bytes

swift
func stringLenghtInBytes(string: String) -> Int {
    return (string as NSString).length
}
<details><summary>View Examples</summary> 
stringLenghtInBytes("Hello")
</details>

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nth element

Returns every nth element from given list.

swift
func everyNth(list: [Any], n: Int) -> [Any] {
    return list.enumerated().compactMap({ ($0.offset + 1) % n == 0 ? $0.element : nil })
}
<details><summary>View Examples</summary> 
swift
everyNth(list: [1, 2, 3, 4, 5, 6], n: 2) // [ 2, 4, 6 ]
everyNth(list: ["a", "b", "c", "d", "e", "f"], n: 3) // [ "c", "f" ]
</details>

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is sorted

Returns 1 if array is sorted in ascending order, -1 if descending order, and 0 if unsorted

swift
func isSorted(arr: [Int]) -> Int {
    var asc: Bool = true
    var prev: Int = Int.min
    for elem in arr {
        if elem < prev {
            asc = false
            break
        }
        prev = elem
    }
    if asc {
        return 1
    }
    var dsc: Bool = true
    prev = Int.max
    for elem in arr {
        if elem > prev {
            dsc = false
            break
        }
        prev = elem
    }
    if dsc {
        return -1
    }

    return 0
}
<details><summary>View Examples</summary> 
swift
isSorted(arr: [1, 2, 2, 4, 8]) // 1
isSorted(arr: [8, 4, 4, 2, 1]) // -1
isSorted(arr: [1, 4, 2, 8, 4]) // 0
</details>

is sorted 2

Returns 1 if array is sorted in ascending order, -1 if descending order, and 0 if unsorted - OPTION 2 shortest

swift
func sortedArray (arr: [Int]) -> Int {
    let sortedArr = arr.sorted(by: {$1>$0})
    return arr == sortedArr ? 1 : arr == sortedArr.reversed() ?  -1 :  0
}
<details><summary>View Examples</summary> 
swift
//Input sortedArray(arr: [1,2,3,4,5]) - Output 1
//Input sortedArray(arr: [5,4,3,2,1]) - Output -1
//Input sortedArray(arr: [6,2,3,4,8]) - Output 0
</details>

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camel case string to snake case

Convert camel case string (ex.'appleStore', 'TimCook') to snake case (ex. apple_store, 'tim_cook')

swift
func camelCaseToSnake(str: String) -> String {
    guard let regex = try? NSRegularExpression(pattern: "([a-z0-9])([A-Z])", options: []) else {
        return str
    }
    let range = NSRange(location: 0, length: str.count)
    return regex.stringByReplacingMatches(in: str, options: [], range: range, withTemplate: "$1_$2").lowercased()
}
<details><summary>View Examples</summary> 
swift
camelCaseToSnake(str: "appleIphoneX")
camelCaseToSnake(str: "camelCaseStringToSnakeCase")
camelCaseToSnake(str: "string")
camelCaseToSnake(str: String())
camelCaseToSnake(str: "firstPullRequestForHacktoberFest🍁☔️🤖")
</details>

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Flip

Flip takes a function as an argument, then makes the first argument the last.

swift
func flip<A,B,C>(_ f:@escaping (A,B) -> C) -> (B,A) -> C {
    return { (b,a) in f(a,b) }
}
<details><summary>View Examples</summary> 
swift
String.init(repeating:"🥳",count:5) == flip(String.init(repeating:count:))(5,"🥳") //true
</details>

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Graph

Returns the neighbors of a vertex

swift
public func neighborsForIndex(_ index: Int) -> [VertexType] {
    return edges[index].map({self.vertices[$0.v]})
}

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Contributors

Lizzie Siegle

Abdulhakim Ajetunmobi

Hatos Barbosa

Paul Schroder

Viktor Sokolov

Sai Sandeep Mutyala

Sören Kirchner

Alexey Ivanov

Júlio John Tavares Ramos

Camilo Andres Ibarra Yepes

Nicolas Combe

William Spanfelner

Natchanon A.

Contributors

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This article is auto-generated from elizabethsiegle/30-seconds-of-swift-code via the GitHub API.Last fetched: 5/31/2026