Swift: Why no elements are adding to my array while using append?

Question

I want to create a Fibonacci Sequence. A user will enter a number, For example, 9 then the Fibonacci Sequence will be displayed, ending with the nearest Fibonacci Sequence number. So, in this case: 0,1,1,2,3,5,8

I am having a problem with storing elements in the 2D array. When loop starts from 0, 0 at 0 index is stored, and when loop comes to 1, then again 1 at index 0 is stored, but it should have stored at index 1. This is causing index out of range error in the upper part of code. Should I use something different than append or something else?

 func fabino(until: Int) {

    if until > 2 {
        for number in 0...until {

            var arrayOfDemoNumbers = [Int]()

            if number > 1 {
               arrayOfDemoNumbers.append(arrayOfDemoNumbers[number - 1] + arrayOfDemoNumbers[number - 2])
                listOfNumbers = listOfNumbers + "\(arrayOfDemoNumbers[number]), "
            }else{
                sum = number + sum
                arrayOfDemoNumbers.append(sum)
               // arrayOfDemoNumbers[number] = sum
                listOfNumbers = listOfNumbers + "\(sum), "
                dump(arrayOfDemoNumbers)
            }
        }}else{
            self.listOfNumbers = "0,1,1"
        }

        labelToChange.text = listOfNumbers

    }

you are initializing an empty arrayOfDemoNumbers every time it loops thus clearing it out. — rmickeyd
– rmickeyd, Commented Jan 10, 2018 at 20:04

rmickeyd · Accepted Answer · 2018-01-10 20:04:40Z

1

 func fabino(until: Int) {
    var arrayOfDemoNumbers = [Int]()

    if until > 2 {
        for number in 0...until {

            if number > 1 {
               arrayOfDemoNumbers.append(arrayOfDemoNumbers[number - 1] + arrayOfDemoNumbers[number - 2])
                listOfNumbers = listOfNumbers + "\(arrayOfDemoNumbers[number]), "
            }else{
                sum = number + sum
                arrayOfDemoNumbers.append(sum)
               // arrayOfDemoNumbers[number] = sum
                listOfNumbers = listOfNumbers + "\(sum), "
                dump(arrayOfDemoNumbers)
            }
        }}else{
            self.listOfNumbers = "0,1,1"
        }

        labelToChange.text = listOfNumbers

    }

answered Jan 10, 2018 at 20:04

rmickeyd

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1 Comment

rmaddy Over a year ago

Good answers explain what the issue was and how the answer fixes it. Please don't just post code.

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