What is Array?
Array is an ordered list with indices / Index
Example of an Array can be a to do list, Shopping list, Amazon Wish List etc.
Let’s say we have an array list of apps
Index: 0 1 2 3
Element: “Reminders” “Mail” “Xcode” “Calendar”
Important Note: Index of first element is always start with zero because way computer scientist deal with data in memory they have offset & offset starts with zero & thats why array starts with zero. Index of an array never exceed the number of elements.
Here is how to declare Array in Swift: We will declare array with let or var keyword then identifier name then equal sign & then square brackets. Each elements are separated with comma.
var apps = ["Reminders", "Mail", "Xcode", "Calendar"] // Array of Strings, Each element is of Type String var number = [1, 2, 300, 4000] // Array of Integers, Each element is of Type Integer var bools = [true, false, false, true] // Array of Boolean values, Each element is of Type Bool var groups = [["John", "Tom", "Steve"], ["Brandon", "Bill"]] // Array inside array
Here is how to copy one array to second array
var secondApps = apps // Key Values of apps array got assigned or copied to secondApp array
Here is how you can declare Empty array for different types
Empty Array of Strings
var apps = [String]()
Empty Array of Integers
var numbers = [Int]()
Empty Array of Booleans
var bools = [Bool]()
Empty Array of Array Group of Strings
var groups = [[String]]()
Here is how you can access elements in Array using use subscript notation
var apps = ["Reminders", "Mail", "Xcode", "Calendar"] let reminder = apps  // Index of First Element let lastElement = apps // Index of last element
Important Note: Fast way to access any element inside array provide that you know exact index of your element. Remember that never let the index in subscript notation exceed the number of elements as program will crash if you do so.
Here is how we can know if index does exceed or not?
Solution to this problem is we can use one property called count.
var apps = ["Reminders", "Mail", "Xcode", "Calendar"] let numberOfElements = apps.count let firstElement = apps // Accessing first element let lastElement = apps[apps.count - 1] // Accessing Last Element of an array let lastElement2 = apps[numberOfElements - 1] // Smart way of accessing Last Element of an array
Here is how you can find out if Array is empty
apps.isEmpty // False
There are two types of Arrays i.e. Mutable & Immutable Array
Mutable: Elements can be changed after initialisation
Immutable Array: Elements cannot be be changed
Here is how to find which array in mutable & which one is immutable array?
Answer is Simple: If you use let (constant) keyword to declare array then it’s immutable array and if you use var (variable) keyword to declare array then it’s mutable array.
Things to do with mutable array or modify mutable array
Here is how you can add new element to existing array by Appending
apps.append("Safari") // Adding new element to array
Here is how you can remove an element at specific index
Here is how you can remove the last element of an Array
apps.removeLast() apps.insert(Keychain, atIndex: 3) // Inserting value at index 3 of an array
Here is how you can remove all elements in Array
Here is how you can replace element at specific index 1
apps = "Sketch"
I hope this blog post will clear all your doubts about Array in Swift Programming Language.
Thanks & Regards