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.
Switch branches/tags
Nothing to show
Clone or download
elizabethsiegle Merge pull request #1 from toseefkhilji/master
Adding example for capitalizeEveryWord
Latest commit 597dac5 Nov 23, 2018
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
30secsofswiftcode.playground README Nov 20, 2018
README.md Adding example for capitalizeEveryWord Nov 22, 2018
swiflangversion.png README Nov 20, 2018

README.md

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 Ctrl + F or command + F 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.

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

📚 List

View contents

Math

View contents

🗃 Object

View contents

📜 String

View contents

📚 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.

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
}
View Examples
bubbleSort([32,12,12,23,11,19,81,76]) //[11, 12, 12, 19, 23, 32, 76, 81]


⬆️ Back to top

chunk

Chunks an array into smaller arrays of a certain size.

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
}
View Examples
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"]]


⬆️ Back to top

filter bools

Remove every value that's not a Boolean.

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


⬆️ Back to top

count occurrences

Count occurrences of a string in an array.

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


⬆️ Back to top

deep flatten

Deep flattens a list with recursion.

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
}
View Examples
deepFlatten(arr: [6, 5, 4, [3, 2], [1]]) //[6, 5, 4, 3, 2, 1]


⬆️ Back to top

difference

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

func difference(arr1: [AnyHashable], arr2: [AnyHashable]) -> Set<AnyHashable> {
    return Set(arr1).symmetricDifference(arr2)
}
View Examples
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


⬆️ Back to top

duplicates

Check for duplicate elements in a given array.

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


⬆️ Back to top

insertion sort

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

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
}
View Examples
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]


⬆️ Back to top

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.

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
}
View Examples
var foo = [1,2,3]
shuffle(arr1: foo) //[2,3,1] , foo = [1,2,3]


⬆️ Back to top

Math

average

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

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


⬆️ Back to top

factorial

Calculates the factorial of a number.

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
}
View Examples
factorial(num: 4) //24
factorial(num: 10) //3628800


⬆️ Back to top

gcd

Calculates the greatest common divisor between two integers with recursion.

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


⬆️ Back to top

lcm1

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

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


⬆️ Back to top

lcm2

Least common multiple of an array using the first lcm.

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


⬆️ Back to top

max n

Returns the maximum element from the provided array.

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


⬆️ Back to top

min n

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

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


⬆️ Back to top

calc median

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

func calcMedian(arr: [Int]) -> Float {
    return Float(arr.sorted(by: <)[arr.count / 2])
}
View Examples ```swift calcMedian(arr: [1,2,3,4,5,6,7,8]) //returns 4.5 ```

⬆️ Back to top

calc better median

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

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])
}
View Examples
calcBetterMedian(arr: [1,2,3,4,5,6,7,8]) //returns 4.5


⬆️ Back to top

🗃 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.

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


⬆️ Back to top

just keys

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

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


⬆️ Back to top

just values

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

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


⬆️ Back to top

📜 String

capitalize first

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

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


⬆️ Back to top

capitalize every word

Capitalizes the first letter of every word in a string.

func capitalizeEveryWord(str: String) -> String {
    return str.capitalized
}
View Examples
capitalizeEveryWord(str: "on a scale from 1 to 10 how would you rate your pain") //On A Scale From...


⬆️ Back to top

count vowels

Retuns number of vowels in provided string.

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
}
View Examples
countVowels(str: "hi mom") //2
countVowels(str: "aeiou") //5


⬆️ Back to top

lower case first letter of first word

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

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


⬆️ Back to top

is lower case

Return true if any character in a string is capitalized.

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


⬆️ Back to top

is upper case

Checks that each character in a string is uppercase.

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


⬆️ Back to top

palindrome

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

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


⬆️ Back to top

drop

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

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


⬆️ Back to top

Contributors