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iOS Swift 2.0 Collections and Control Flow Introduction to Collections Working with Arrays

Posted by Wardah M
Wardah M
477 Points

Challenge Question Confusion

In this challenge it asks to do "We also learned about reading values from an array. Retrieve the 5th item (remember array indexes start at 0) and assign the result to a constant named value."

First, what does it mean to Retrieve? I'm having confusion about that also This is my code but an error shows up.

Please help

arrays.swift 
// Enter your code below

var arrayOfInts = [1,2,3,4,5,6]

arrayOfInts.append(7)

arrayOfInts += [8]

let value = [5]

3 Answers

Bill Merickel
Bill Merickel
11,420 Points

For your first question, see below.

Value: 1, 2, 3, 4, 5, 6 Index: 0, 1, 2, 3, 4, 5 As you can see, the 5th value (which is 5) is the 4th index of the array. Hope that clarifies. If you're still confused, experiment in Xcode with array indexes and values.

For your second question, the reason why you might have an error is because you're trying to remove the arrayOfInts' seventh index, which doesn't exist. If you look at my model above, you should have 5 indexes. If you want to remove the value of 6 from arrayOfInts, try this.

arrayOfInts.removeAtIndex(5)

Since the 5th index has a value of 6, you will erase the value of 6 from the array. Hope this all helps, and please contact me if you have more questions!

Wardah M
Wardah M
477 Points

thank you! Really appreciate it!

Bill Merickel
Bill Merickel
11,420 Points
Bill Merickel
Bill Merickel
11,420 Points

Retrieve means extract the value from the array and assign it as a value to a new constant or variable. The reason why your code doesn't work is because when you declare a new constant or variable and you want to assign a value from a previous array, you need to specify the array name. Your last line should look like this.

let value = arrayOfInts[4]

Also remember, array indexes start at 0, so when you count to 5, 4 is your value since 0 is the first value. Any other questions, let me know!

Wardah M
Wardah M
477 Points

Hi, thanks for the help. But, when I count to 5 isn't 6 the value how is it 4?

And also, The other question is "To remove an item, use the method removeAtIndex() and put the index number in between parentheses that you want to remove."

This is the code that I did, but it is showing an error:

// Enter your code below

var arrayOfInts = [1,2,3,4,5,6]

arrayOfInts.append(7)

arrayOfInts += [7]

let value = arrayOfInts[4]

arrayOfInts.removeAtIndex(7)

let discardValue = arrayOfInts

Please help. Thanks!

Bill Merickel
Bill Merickel
11,420 Points
Bill Merickel
Bill Merickel
11,420 Points

Happy to help! :)