GitHub - elizabethsiegle/30-seconds-of-swift-code: A Swift implementation of 30-...
source link: https://github.com/elizabethsiegle/30-seconds-of-swift-code
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README.md
30-seconds-of-swift-code 
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.
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 contentsbubbleSortfilterBoolschunkcountOccurrencesdeepFlattendifferenceduplicatesinsertionSortfisherYatesShufflecalcMediancalcBetterMedianaveragefactorialgcdlcm1lcm2maxnminnallUniquejustKeysjustValuescapitalizeFirstcapitalizeEveryWordcountVowelslowerCaseFirstLetterOfFirstWordisLowerCaseisUpperCasepalindromedrop
➗ Math
View contents? Object
View contents? String
View contentscapitalizeFirstcapitalizeEveryWordcountVowelslowerCaseFirstLetterOfFirstWordisLowerCaseisUpperCasepalindrome
? 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 }
bubbleSort([32,12,12,23,11,19,81,76]) //[11, 12, 12, 19, 23, 32, 76, 81]
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 }
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"]]
filter bools
Remove every value that's not a Boolean.
func filterBools(_ inputArr: [Any]) -> [Any] { return inputArr.compactMap { $0 as? Bool } }
filterBools([false, 2, "lol", 3, "a", "s", 34, false, true]) //[false, false, true]
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 } }
countOccurrences(arr: ["FOO", "FOO", "BAR"], into: "FOO") //2
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 }
deepFlatten(arr: [6, 5, 4, [3, 2], [1]]) //[6, 5, 4, 3, 2, 1]
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) }
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
duplicates
Check for duplicate elements in a given array.
func duplicates(arr1: [AnyHashable]) -> Bool { return arr1.count != (Set<AnyHashable>(arr1)).count }
duplicates(arr1: [5, 4, 3, 2]) //false duplicates(arr1: ["hermione", "hermione", "ron", "harry"]) //true
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 }
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]
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 }
var foo = [1,2,3] shuffle(arr1: foo) //[2,3,1] , foo = [1,2,3]
➗ 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) }
average(arr: [5, 4, 3, 2, 1]) //3
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 }
factorial(num: 4) //24 factorial(num: 10) //3628800
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 }
gcd(num1: 228, num2: 36) //12 gcd(num1: -5, num2: -10)
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) }
lcm1(num1: 12, num2: 7) //84
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) } }
lcm2(arr1: [4, 3, 2]) //12
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 }
maxn(arr1: [2, 9, 5]) //9 [2, 9, 5].max() //9
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 }
minn(arr1: [8, 2, 4, 6]) //2 [8, 2, 4, 6].min() //2
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]) }
⬆️ 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]) }
calcBetterMedian(arr: [1,2,3,4,5,6,7,8]) //returns 4.5
? 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 }
allUnique(arr: [5, 4, 3, 2]) //true allUnique(arr: ["lol", "rofl", "lol"]) //false
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) }
var dict: Dictionary<String, String> = ["Mulan": "Mushu", "Anna": "Olaf", "Pocahontas": "Fleeko"] justKeys(dict: dict) //[Anna, Mulan, Pocahontas]
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) }
justValues(dict: dict) //[Olaf, Mushu, Fleeko]
? 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: " ") }
capitalizeFirst(str: "i like cheesE") //I like cheesE
capitalize every word
Capitalizes the first letter of every word in a string.
func capitalizeEveryWord(str: String) -> String { return str.capitalized }
capitalizeEveryWord(str: "on a scale from 1 to 10 how would you rate your pain")
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 }
countVowels(str: "hi mom") //2 countVowels(str: "aeiou") //5
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: " ") }
lowerCaseFirstLetterOfFirstWord(str: "Christmas Switch was a solid movie") //christmas Switch...
is lower case
Return true if any character in a string is capitalized.
func isLowerCase(str: String) -> Bool { return str == str.lowercased() }
isLowerCase(str: "I LOVE CHRISTMAS") //false isLowerCase(str: "<3 lol") //true
is upper case
Checks that each character in a string is uppercase.
func isUpperCase(str: String) -> Bool { return str == str.uppercased() }
isUpperCase(str: "LOLOLOL") //true isUpperCase(str: "lmao") //false isUpperCase(str: "Rofl") //false
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() }
palindrome(str: "racecar") //true palindrome(str: "Madam") //true palindrome(str: "lizzie") //false
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 }
drop(arr: [5, 4, 3, 2, 1, 0], num: 1) drop(arr: ["Huey", "Dewey", "Louie"], num: 3)
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