Using UserDefault to Store & Retrieve Data in Swift: A Quick Guide

Swift is an incredibly powerful and versatile programming language, and one of its advantages is that it allows developers to store and retrieve data from user defaults. This data can be used to save settings, store user preferences, or even to save state information in an app. In this article, we’ll take a look at how to use UserDefault in Swift to store and retrieve data.

UserDefault is a class that is included in the Swift Standard Library. It’s designed to be easy to use and efficient. It provides a way to store key-value pairs of data, and it’s stored in a persistent storage location. When an app is launched, all the data stored in UserDefault is loaded into memory. This makes it an ideal place to store data that needs to be available across multiple sessions, such as user preferences or settings.

To use UserDefault in your code, you need to create an instance of it. You can do this by calling its constructor, which takes a single parameter – a string representing the name of the UserDefault. The following example creates a UserDefault with the name “MyUserDefault”:

let userDefault = UserDefault(name: "MyUserDefault")

Once you have an instance of UserDefault, you can use it to store and retrieve data. To store data, you can call the setValue(_:forKey:) method. This method takes two parameters – a value to store, and a key to associate it with. The following example stores the string “Hello World” with the key “myString”:

userDefault.setValue("Hello world", forKey: "myString")

You can also store other types of data, such as integers, booleans, and arrays. For example, the following code stores an array of strings with the key “myArray”:

let myArray = ["one", "two", "three"]
userDefault.setValue(myArray, forKey: "myArray")

Once you’ve stored data in UserDefault, you can retrieve it by calling the value(forKey:) method. This method takes a single parameter – the key associated with the data you want to retrieve. The following example retrieves the string stored with the key “myString”:

let myString = userDefault.value(forKey: "myString") as? String

In addition to storing and retrieving data, UserDefault also provides a few useful methods for managing data. For example, the removeObject(forKey:) method removes an object from UserDefault. You can also call the synchronize() method to force UserDefault to write its contents to disk.

Using UserDefault to store and retrieve data in Swift is a great way to save user preferences and settings. The class is easy to use and provides a simple way to persist data between sessions. With just a few lines of code, you can quickly store and retrieve data using UserDefault.