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- //: Playground - noun: a place where people can play
- import Cocoa
- //OPTIONALS
- let a: Int? = 1
- let b: Int? = 2
- //TUPLE
- let tuple = (number:55, name:"name")
- //OPTIONAL BINDING
- if let firstNumber = Int("4"), let secondNumber = Int("42"), firstNumber < secondNumber && secondNumber < 100 {
- print("\(firstNumber) < \(secondNumber) < 100")
- }
- // String to Int
- let m = Int("23")
- //NIL-COALESCAPING OPERATOR
- let n = a ?? b
- //************* STRINGS **************************
- var emptyString = "" // empty string literal
- var anotherEmptyString = String() // ”
- let exclamationMark: Character = "!" //CHAR type
- let catCharacters: [Character] = ["C", "a", "t", "!", "🐱"] //char array
- for character in "Dog!🐶".characters { // iterate of chars in string
- print(character)
- }
- let multiplier = 3
- let message = "\(multiplier) times 2.5 is \(Double(multiplier) * 2.5)" //string interpolation
- let dollarSign = "\u{24}" // $, Unicode scalar U+0024”
- let animal = "animal"; print(animal.characters.count) //string count
- let greeting = "0123456789" //string indexing
- greeting[greeting.startIndex]
- greeting[greeting.index(before: greeting.endIndex)]
- greeting[greeting.index(after: greeting.startIndex)]
- let index = greeting.index(greeting.startIndex, offsetBy: 7)
- greeting[index]
- for index in greeting.characters.indices {
- print("\(greeting[index]) ", terminator: "")
- }
- var welcome = "hello" //string insert
- welcome.insert("!", at: welcome.endIndex)
- welcome.insert(contentsOf:" there".characters, at: welcome.index(before: welcome.endIndex)) //insert
- welcome.remove(at: welcome.index(before: welcome.endIndex))
- welcome.utf8 //“UTF-8 representation of a String by iterating over its utf8 property. ”
- //ARRAYS
- var someInts = [Int]() //initialize empty array
- someInts.count // array length
- someInts.append(3)
- var shoppingList: [String] = ["Eggs", "Milk"]
- var shoppingList2 = ["Eggs", "Milk"] // shorthand with type inference
- shoppingList.count
- shoppingList.isEmpty
- shoppingList.append("Flour")
- shoppingList += ["Chocolate Spread", "Cheese", "Butter"]
- var firstItem = shoppingList[0]
- shoppingList[2...4] = ["Bananas", "Apples"]
- shoppingList.insert("Maple Syrup", at: 0)
- let mapleSyrup = shoppingList.remove(at: 0)
- let apples = shoppingList.removeLast()
- for item in shoppingList { //iterate over array
- print(item)
- }
- for (index, value) in shoppingList.enumerated() { //iterate using index
- print("Item \(index + 1): \(value)")
- }
- //************************** SETS **********************
- var letters = Set<Character>()
- letters.count
- letters.insert("a")
- letters = []
- var favoriteGenres: Set<String> = ["Rock", "Classical", "Hip hop"]
- favoriteGenres.isEmpty
- favoriteGenres.insert("Jazz")
- favoriteGenres.remove("Rock")
- favoriteGenres.contains("Funk")
- for genre in favoriteGenres { print("\(genre)")}
- let oddDigits: Set = [1, 3, 5, 7, 9]
- let evenDigits: Set = [0, 2, 4, 6, 8]
- oddDigits.union(evenDigits).sorted()
- oddDigits.intersection(evenDigits).sorted()
- let houseAnimals: Set = ["🐶", "🐱"]
- let farmAnimals: Set = ["🐮", "🐔", "🐑", "🐶", "🐱"]
- let cityAnimals: Set = ["🐦", "🐭"]
- houseAnimals.isSubset(of: farmAnimals)
- farmAnimals.isSuperset(of: houseAnimals)
- farmAnimals.isDisjoint(with: cityAnimals)
- //****************** DICTIONARY ******************************
- var namesOfIntegers = [Int: String]() // init empty dict
- namesOfIntegers[16] = "sixteen"
- var airports = ["YYZ": "Toronto Pearson", "DUB": "Dublin"]
- airports.count
- airports.isEmpty
- airports["LHR"] = "London"
- var threeDoubles = Array(repeating: 0.0, count: 3)
- var anotherThreeDoubles = Array(repeating: 2.5, count: 3)
- var sixDoubles = threeDoubles + anotherThreeDoubles //new array from adding 2 arrays
- //TRY CATCH
- func canThrowAnError() throws {}
- do {
- try canThrowAnError()
- // no error was thrown
- } catch {}
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