Examples of declarations:
1. A 2D array of unspecified size, that contains integers:
var board = [[Int]]() var board1:[[Int]] = [[Int]]()
The second version is more formal and more understandable: the left of the equal sign is saying: create a variable called board1, and of type 2-dimensional array. The RHS is saying: initialise the variable with a 2-dimensional array of no elements.
In the first (and preferred) version, the compiler assumes that ‘board‘ is of type 2-dimensional array, because it is being initialised with a 2-dimensional array (of no elements).
2. A 2D array initialised to:
1 13
2
56 57 58
(where the first row has two columns (1 and 13), the second row has one column (2), and the third row has three columns (56,57, and 58)):
var vCR = [[1,13],[2],[56,57,58]] var vCR1:[[Int]] = [[1,13],[2],[56,57,58]]
As in the first example, the first version is preferred, while the second version is more formal, explicitly giving the variable a type (2-dimensional array).
3. A 3×3 array that is filled with 4’s:
var anArray = [[Int]](count: 3, repeatedValue: [Int](count: 3, repeatedValue: 4))
The above Right Hand Side says:
- initialise anArray with a 2-dimensional array of integers (‘[[Int]]‘), and
- fill each of the 3 rows (‘count:3‘)
- with an integer array (‘repeatedValue:[Int]‘)
- of 3 columns each containing ‘4’ (‘count:3 repeatedValue:4‘).
anArray equals [[4,4,4],[4,4,4],[4,4,4]]. That is, 3 rows, with each row containing a column of 3 elements ‘4’.
I found a re-read of Swift by Example, on single-dimensional arrays, handy at this point.
4. A 3x5x4 array that is filled with “a string”:
var aBigArray = [[[String]]](count: 3, repeatedValue: [[String]](count: 5, repeatedValue: [String](count: 4, repeatedValue: "a string")))
