Mảng (Array) trong Swift

// Array literal
let numbers = [1, 2, 3, 4, 5]
let fruits = ["Apple", "Banana", "Orange"]
 
// Empty array
var emptyArray: [Int] = []
var anotherArray = [String]()
 
// Array với giá trị mặc định
let zeros = Array(repeating: 0, count: 5)  // [0, 0, 0, 0, 0]

let immutableArray = [1, 2, 3]
// immutableArray.append(4)  // Error!
 
var mutableArray = [1, 2, 3]
mutableArray.append(4)  // OK

let fruits = ["Apple", "Banana", "Orange"]
 
print(fruits[0])     // Apple
print(fruits[1])     // Banana
print(fruits.first)  // Optional("Apple")
print(fruits.last)   // Optional("Orange")

var numbers = [1, 2, 3]
 
numbers.append(4)           // [1, 2, 3, 4]
numbers.insert(0, at: 0)    // [0, 1, 2, 3, 4]
numbers += [5, 6]           // [0, 1, 2, 3, 4, 5, 6]

var numbers = [1, 2, 3, 4, 5]
 
numbers.remove(at: 0)       // [2, 3, 4, 5]
numbers.removeLast()        // [2, 3, 4]
numbers.removeAll()         // []

var fruits = ["Apple", "Banana", "Orange"]
 
fruits[1] = "Mango"
print(fruits)  // ["Apple", "Mango", "Orange"]

let fruits = ["Apple", "Banana", "Orange"]
 
// For-in
for fruit in fruits {
    print(fruit)
}
 
// Với index
for (index, fruit) in fruits.enumerated() {
    print("\(index): \(fruit)")
}

let numbers = [1, 2, 3, 4, 5]
 
print(numbers.count)         // 5
print(numbers.isEmpty)       // false
print(numbers.contains(3))   // true
 
let doubled = numbers.map { $0 * 2 }       // [2, 4, 6, 8, 10]
let evens = numbers.filter { $0 % 2 == 0 } // [2, 4]
let sum = numbers.reduce(0, +)             // 15

let numbers = [1, 2, 3, 4, 5]
 
let slice = numbers[1...3]   // [2, 3, 4]
let prefix = numbers.prefix(3)  // [1, 2, 3]
let suffix = numbers.suffix(2)  // [4, 5]

var numbers = [5, 2, 8, 1, 9]
 
numbers.sort()               // [1, 2, 5, 8, 9] (in-place)
let sorted = numbers.sorted() // Trả về array mới
 
// Sắp xếp giảm dần
numbers.sort(by: >)          // [9, 8, 5, 2, 1]