How to use for loop to create Int array in Swift 3

Question

I know this is a very basic question,

But I try lot methods, and always show:

"fatal error: Array index out of range"

I want to create a 0~100 int array

e.q. var integerArray = [0,1,2,3,.....,100]

and I trying

var integerArray = [Int]()
for i in 0 ... 100{
integerArray[i] = i
}

There are also appear : fatal error: Array index out of range

Thanks for help

Complete code:

class AlertViewController: UIViewController,UIPickerViewDelegate, UIPickerViewDataSource {

@IBOutlet weak var integerPickerView: UIPickerView!
@IBOutlet weak var decimalPickerView: UIPickerView!

var integerArray = [Int]()
var decimalArray = [Int]()

override func viewDidLoad() {
    super.viewDidLoad()
    giveArrayNumber()
    integerPickerView.delegate = self
    decimalPickerView.delegate = self
    integerPickerView.dataSource = self
    decimalPickerView.dataSource = self
}

func giveArrayNumber(){
    for i in 0 ... 100{
        integerArray[i] = i
    }
}

Reading the documentation helps: "You can add a new item to the end of an array by calling the array’s append(_:) method:" and "You can’t use subscript syntax to append a new item to the end of an array." — Martin R
– Martin R, Commented Mar 9, 2017 at 10:04

Nirav D · Accepted Answer · 2017-03-09 09:56:36Z

33

Your array is empty and you are subscripting to assign value thats why you are getting "Array index out of range" crash. If you want to go with for loop then.

var integerArray = [Int]()
for i in 0...100 {
    integerArray.append(i)
}

But instead of that you can create array simply like this no need to use for loop.

var integerArray = [Int](0...100)

answered Mar 9, 2017 at 9:56

Nirav D

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1 Comment

Nirav D Over a year ago

@JimmyHo Welcome mate :)

Andrew · Accepted Answer · 2023-04-14 20:08:14Z

4

Solution 1:

var integerArray = Array(0...100)

Solution 2:

var integerArray = [Int](0...100)

Solution 3(worst):

var integerArray = (0...100).map{ $0 }

edited Apr 14, 2023 at 20:08

answered Sep 1, 2020 at 11:26

Andrew

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1 Comment

kakubei Over a year ago

The accepted answer is good but I think this is much more useful in general :)

Prashant Tukadiya · Accepted Answer · 2017-03-09 10:25:43Z

0

Because your array is empty, so the "integerArray[i] (where i is 1 for example)" doesn't exist.

You have to write something like this :

 func giveArrayNumber() {
    for i in 0 ... 100{
       integerArray.append(i)
    }
 }

edited Mar 9, 2017 at 10:25

Prashant Tukadiya

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answered Mar 9, 2017 at 10:00

Leonardo

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