Arrays

CREATING ARRAYS

let evenNumbers = [2, 4, 6, 8]

var subscribers: [String] = []

let allZeros = Array(repeating: 0, count: 5)

let vowels = ["A", "E", "I", "O", "U"]

let array1 = [[int]]() // Valid
//let array2 = [] // Invalid: the type cannot be inferred
let array3: [String] = [] // Valid

ACCESSING ELEMENTS

var players = ["Alice", "Bob", "Cindy", "Dan"]

print(players.isEmpty)
// > false

if players.count < 2 {
  print("We need at least two players!")
} else {
  print("Let's start!")
}
// > Let's start!

var currentPlayer = players.first

print(currentPlayer as Any)
// > Optional("Alice")

print(players.last as Any)
// > Optional("Dan")

currentPlayer = players.min()
print(currentPlayer as Any)
// > Optional("Alice")

print([2, 3, 1].first as Any)
// > Optional(2)
print([2, 3, 1].min() as Any)
// > Optional(1)

if let currentPlayer = currentPlayer {
  print("\(currentPlayer) will start")
}
// > Alice will start

var firstPlayer = players[0]
print("First player is \(firstPlayer)")
// > First player is "Alice"

//var player = players[4]
// > fatal error: Index out of range

let upcomingPlayersSlice = players[1...2]
print(upcomingPlayersSlice[1], upcomingPlayersSlice[2])
// > "Bob Cindy\n"

let upcomingPlayersArray = Array(players[1...2])
print(upcomingPlayersArray[0], upcomingPlayersArray[1])
// > "Bob Cindy\n"


func isEliminated(player: String) -> Bool {
  return !players.contains(player)
}

print(isEliminated(player: "Bob"))
// > false

players[1...3].contains("Bob")

MANIPULATING ELEMENTS

players.append("Eli")

players += ["Gina"]

print(players)
// > ["Alice", "Bob", "Cindy", "Dan", "Eli", "Gina"]

players.insert("Frank", at: 5)

REMOVING ELEMENTS

var removedPlayer = players.removeLast()
print("\(removedPlayer) was removed")
// > Gina was removed

removedPlayer = players.remove(at: 2)
print("\(removedPlayer) was removed")
// > Cindy was removed

UPDATING ELEMENTS

print(players)
// > ["Alice", "Bob", "Dan", "Eli", "Frank"]
players[4] = "Franklin"
print(players)
// > ["Alice", "Bob", "Dan", "Eli", "Franklin"]

players[0...1] = ["Donna", "Craig", "Brian", "Anna"]
print(players)
// > ["Donna", "Craig", "Brian", "Anna", "Dan", "Eli", "Franklin"]

let playerAnna = players.remove(at: 3)
players.insert(playerAnna, at: 0)
print(players)
// > ["Anna", "Donna", "Craig", "Brian", "Dan", "Eli", "Franklin"]

players.swapAt(1, 3)
print(players)
// > ["Anna", "Brian", "Craig", "Donna", "Dan", "Eli", "Franklin"]

players.sort()
print(players)
// > ["Anna", "Brian", "Craig", "Dan", "Donna", "Eli", "Franklin"]

ITERATION

let scores = [2, 2, 8, 6, 1, 2, 1]

for player in players {
  print(player)
}
// > Anna
// > Brian
// > Craig
// > Dan
// > Donna
// > Eli
// > Franklin

for (index, player) in players.enumerated() {
  print("\(index + 1). \(player)")
}
// > 1. Anna
// > 2. Brian
// > 3. Craig
// > 4. Dan
// > 5. Donna
// > 6. Eli
// > 7. Franklin

func sumOfElements(in array: [Int]) -> Int {
  var sum = 0
  for number in array {
    sum += number
  }
  return sum
}

print(sumOfElements(in: scores))
// > 2