In this post, we'll explore two essential collection types in Swift: Arrays and Sets. To make the explanation more engaging, we'll use examples related to the popular game "The Last of Us."
Arrays
Arrays are ordered collections of elements. They store a list of values of the same type in an ordered sequence. Swift arrays are mutable, meaning you can add, remove, and change elements.
Creating Arrays
You can create an array by specifying the type of its elements in square brackets. For example, an array of strings would be [String]. Let's create an array of characters from "The Last of Us":
var characters: [String] = ["Joel", "Ellie", "Tess", "Tommy", "Maria"]
Alternatively, you can use the shorthand syntax:
var characters = ["Joel", "Ellie", "Tess", "Tommy", "Maria"]
Accessing and Modifying Arrays
You can access elements in an array using their index, which starts from 0. For example, the first character in our array is "Joel":
let firstCharacter = characters[0] // "Joel"
To add a new element to the array, use the append method:
characters.append("Dina")
You can also insert elements at a specific index using the insert(_:at:) method:
characters.insert("Jesse", at: 2)
To remove an element, use the remove(at:) method:
characters.remove(at: 1) // Removes "Ellie"
Iterating Over Arrays
You can use a for-in loop to iterate over the elements of an array:
for character in characters {
print(character)
}
Sets
Sets are unordered collections of unique elements. They store a collection of distinct values of the same type but don't maintain a specific order. Sets are ideal when you want to ensure that each element appears only once.
Creating Sets
You can create a set using the Set keyword followed by the type of its elements in angle brackets. For example, a set of strings would be Set<String>. Let's create a set of locations from "The Last of Us":
var locations: Set<String> = ["Boston", "Pittsburgh", "Jackson", "Salt Lake City"]
Accessing and Modifying Sets
You can add an element to a set using the insert method:
locations.insert("Seattle")
To remove an element, use the remove method:
locations.remove("Pittsburgh")
Since sets are unordered, you can't access elements using an index. Instead, you can use the contains method to check if an element is in the set:
if locations.contains("Jackson") {
print("Jackson is in the set.")
}
Iterating Over Sets
You can use a for-in loop to iterate over the elements of a set:
for location in locations {
print(location)
}
Conclusion
Similarities:
Store multiple values: Both Arrays and Sets are used to store multiple values of the same type in a single collection.
Homogeneous: Both can only store values of a single, specific type.
Differences:
Ordering of elements:
Array: An array maintains the order of its elements, meaning the position of each element is set when it's added to the array.
Set: A set does not maintain any particular order for its elements; instead, it ensures that each element is unique within the collection.
Duplicates:
Array: An array can contain duplicate values.
Set: A set cannot contain duplicate values; each element in a set must be unique.
Accessing elements:
Array: Elements in an array can be accessed using an index.
Set: Elements in a set cannot be accessed using an index; instead, you must iterate over the set to access its elements.
Performance:
Array: Searching for a specific element in an array can take more time because it may need to check each element until it finds a match.
Set: Searching for a specific element in a set is typically faster due to its use of hashing to store elements.
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