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iOS Swift Basics (retired) Collections Modifying an Array

Posted by xiaohu li
xiaohu li
Courses Plus Student 569 Points

todo.append

my answer for this is : todo.append ("Debug App","Fix Bugs"), I'm not sure which part is wrong... I followed what the video taught, but the result is wrong.

arrays.swift 
var todo = ["Learn Swift", "Build App", "Deploy App"]

2 Answers

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

the documentation on the append method looks like this

append(_:)

Adds a new item as the last element in an existing array.

the append method takes one argument. you could append an array containing both items like so:

var todo = ["Learn Swift", "Build App", "Deploy App"]
todo.append (["Debug App","Fix Bugs"])

you could also use +=

var todo = ["Learn Swift", "Build App", "Deploy App"]
todo += ["Debug App","Fix Bugs"]

or append them separately

using +=:

var todo = ["Learn Swift", "Build App", "Deploy App"]
todo += "Debug App"
todo += "Fix Bugs"

using append:

var todo = ["Learn Swift", "Build App", "Deploy App"]
todo.append("Debug App")
todo.append("FixBugs")
xiaohu li
xiaohu li
Courses Plus Student 569 Points

Thank you very much! So I need to use [] if there are more than one items, () if there is one item, right?

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

yes if you want to append more than one item to an array, you need to append an array of items (an array literal has [ ] with items inside it). if its just one item, you dont need to append an array, you can append an item directly

xiaohu li
xiaohu li
Courses Plus Student 569 Points

Thank you very much for your help!

Chris Shaw
Chris Shaw
26,676 Points
Chris Shaw
Chris Shaw
26,676 Points

Hi xiaohu li,

There are two ways you can append new items to an Array, the first is the append function which only accepts one argument of the same type, e.g. an array or string.

todo.append("Debug App")
todo.append("Fix Bugs")

The second method is the shortcut which uses the += operator to concatenate the arrays together.

todo += ["Debug App", "Fix Bugs"]

Happy coding!

xiaohu li
xiaohu li
Courses Plus Student 569 Points

Thank you very much! That helped me a lot!