Working with Swift Dictionaries: Basics and Iteration

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by The Captain

May 20, 2024
Working with Swift Dictionaries

Working with Swift Dictionaries

Dictionaries in Swift are used to store key-value pairs. Each value in a dictionary is associated with a unique key, which allows for efficient retrieval of values based on their corresponding keys. In this tutorial, we will explore how to work with dictionaries in Swift.

Creating a Dictionary

To create a dictionary in Swift, you can use the following notation:

var person: [String: Any] = ["name": "John Doe", "age": 30, "isStudent": true]

In the above example, we have created a dictionary person with keys "name", "age", and "isStudent" mapping to values "John Doe", 30, and true respectively. The dictionary is of type [String: Any], meaning the keys are of type String and the values can be of any type.

Accessing and Modifying Values

You can access values in a dictionary by providing the key in square brackets:

let name = person["name"] as? String
print(name) // Output: Optional("John Doe")

To modify a value in a dictionary, you can simply assign a new value to the key:

person["age"] = 31
print(person) // Output: ["name": "John Doe", "age": 31, "isStudent": true]

Iterating Over a Dictionary

You can iterate over a dictionary using a for loop:

for (key, value) in person {
    print("Key: \(key), Value: \(value)")

This will print each key-value pair in the dictionary.


In this tutorial, we covered the basics of working with dictionaries in Swift, including creating, accessing, and modifying values, as well as iterating over a dictionary. Dictionaries are a powerful data structure in Swift that allow for efficient storage and retrieval of key-value pairs.