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Swift Programming

Xcode

iOS

Arrays

What we’ll learn:

Table of contents

  1. What are arrays?
  2. Create an Array
    1. Access an Array
    2. Append value in an Array
    3. Remove Value in an Array
    4. Change the Value in an Array
  3. Data Types and Properties
    1. Common Data Types
    2. Count Property
    3. isEmpty Property
    4. Contains Property
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What are arrays?

Arrays are the most commonly used data types in programming. You use arrays when you want to organize a collection of values of the same data type. Values could be of any data type – from integers, strings to objects.

Syntax

var arrayName: [type] = [value, value, value]

Create an Array

Create an Empty Array

To create an empty array, specify the data type in your array declaration. We can create an array in two ways:

//option 1
var numbers: [Int] = []

// option 2
var colors = [String]()

Create an Array of String Elements

To create an array with integer elements, surround your values with an enclosing and closing bracket separated by commas.

var colors: [String] = ["blue", "green", "red"]

{ Access or Insert }

Access an Array

To access a specific element of an array, address your array name followed by a subscript with the index position of the value you want to retrieve.

Any value outside of the index rage will result in an error.

//access element at index 1
colors[1]

print(colors[1])
// prints green

Append value in an Array

appending value will be added to the end of the array

// Use the assign equals operator (+=) to append the string "purple" to the colors array.
colors += ["purple"]

The appending signature is equivalent to:

// same as the code above 
colors = colors + ["purple"]

Insert Value at specific index of an Array

Use the .insert ("_", at:_) method to insert an element at a specific index. The elements at that index are shifted to make room.

// insert "red" at index 1 (note: index starts at 0)
colors.insert("purple", at: 1)

{ Remove Value }

Remove Value in an Array

Remove Value at Specific Index

To remove elements from a specific index of an array, use the remove(at: ___) method.

// remove value at index 1
colors.remove(at: 1)

Remove the Last Value

If you want to remove the last value of an array, use the removeLast() method.

colors.removeLast()

{ Change Value }

Change the Value in an Array

Change Value of a Specific Index

// change the value at index 0
colors[0] = "orange"

Change Range of Values

// change a range of values
colors[1...2] = ["red", "white", "blue"]

{ Data Types }

Data Types and Properties

Common Data Types

With Swift’s type inference, the data type can be removed if default values are given.

var arrayOfInts: [Int] = [1,2,3,4,5]
var arrayOfStrings: [String] = ["here is one string", "another string", "and another"]
var arrayOfCharacters: [Character] = ["d","f", "g"]
var arrayDoubles: [Double] = [0.1, 0.22, 0.333]
var arrayBool: [Bool] = [true, false, true, true]

{ Array Properties }

Count Property

//returns number of elements in Array
colors.count

isEmpty Property

// returns true or false (boolean value) 
colors.isEmpty

Contains Property

// returns a boolean value indicating whether the array contains the given element.
colors.contains("pink)


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