//: 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 {}