Swift - Arrays

Links

Swift (Programmiersprache)

Arrays

var symbols = ["apple","coin","cherry"]
var symbolIndex = [0,1,2]
var backgrounds = [Color.white,Color.green,Color.red]
var pickerData = [String]() // initialisiert ein leeres Array für String Elemente

Array mit repeating / count füllen

var zeros = Array(repeating:0, count:9) // creates an Array with 9 elements initialised to 0
var colors = Array(repeating: Color.black, count: 12) // 12 Elements initialised to Color.black

Map Function

Die Array.map Funktion bearbeitet jedes Element eines Array.

// Instead of 
backgrounds[0] = Color.white
backgrounds[1] = Color.white
backgrounds[2] = Color.white
// you can use a map function on each element of the array instead:
backgrounds = self.backgrounds.map({ _ in Color.white})

// random values
self.symbolIndex = self.symbolIndex.map({
  _ in Int.random(in: 0...self.symbols.count-1)
})

Multidimensionale Arrays

https://stackoverflow.com/questions/25127700/two-dimensional-array-in-swift

Define mutable array

// 2 dimensional array of arrays of Ints 
var arr = [[Int]]()

OR:

// 2 dimensional array of arrays of Ints 
var arr: [[Int]] = []

OR if you need an array of predefined size (as mentioned by @0x7fffffff in comments):

// 2 dimensional array of arrays of Ints set to 0. Arrays size is 10x5
var arr = Array(count: 3, repeatedValue: Array(count: 2, repeatedValue: 0))

// ...and for Swift 3+:
var arr = Array(repeating: Array(repeating: 0, count: 2), count: 3)

Change element at position

arr[0][1] = 18

OR

let myVar = 18
arr[0][1] = myVar

Change sub array

arr[1] = [123, 456, 789]

OR

arr[0] += 234

OR

arr[0] += [345, 678]

If you had 3x2 array of 0(zeros) before these changes, now you have:

[
  [0, 0, 234, 345, 678], // 5 elements!
  [123, 456, 789],
  [0, 0]
]

So be aware that sub arrays are mutable and you can redefine initial array that represented matrix. Examine size/bounds before access

let a = 0
let b = 1

if arr.count > a && arr[a].count > b {
    println(arr[a][b])
}

Remarks: Same markup rules for 3 and N dimensional arrays.

Array Funktionen

Shuffle

var numbers = [1, 2, 3, 4, 5]

numbers.shuffle()
print(numbers)  // [5, 3, 1, 4, 2] (the order of the elements is randomized)