Getting Data from UserDefaults

Getting data from UserDefaults is very simple. The following methods are used as the getter methods in UserDefaults.

SN	Method	Description
1	func object(forKey: String) -> Any?	It returns the object associated with the specified key.
2	func url(forKey: String) -> URL?	It returns the url associated with the specified key.
3	func array(forKey: String) -> [Any]?	It returns the array associated with the specified key.
4	func dictionary(forKey: String) -> [String : Any]?	It returns the dictionary associated with the specified key.
5	func string(forKey: String) -> String?	It returns the string associated with the specified key.
6	func stringArray(forKey: String) -> [String]?	It returns the string array associated with the specified key.
7	func data(forKey: String) -> Data?	It returns the binary data associated with the specified key.
8	func bool(forKey: String) -> Bool	It returns the boolean value associated with the specified key.
9	func integer(forKey: String) -> Int	It returns the integer value associated with the specified key.
10	func float(forKey: String) -> Float	It returns the float value associated with the specified key.
11	func double(forKey: String) -> Double	It returns the double value associated with the specified key.
12	func dictionaryRepresentation() -> [String : Any]	It returns the dictionary representation of the UserDefualts.

Since the UserDefaults use the data types to retrieve the value stored associated with the key. However, the value for the specified key might not exist. Hence, we need to use the optional binding while retrieving the value from the UserDefaults.

if let token = UserDefaults.standard.string(forKey: "userToken"){
debugPrint(token)
        }

In real-time projects, we use UserDefaults in a singleton Shared Preference class. Let's consider the following example where we create an explicit SharedPreferenceManager class and put all the code related to user defaults there.

SharedPreferenceManager.swift

import Foundation

class SharedPreferenceManager: NSObject {
    class var sharedIntance : SharedPreferenceManager {
        struct Static {
            static let instance = SharedPreferenceManager()
        }
        return Static.instance
    }
    
    let sharedPreferenc = UserDefaults.standard
    
    //MARK:- clear all Data.
    func clearAllPreference() {
        if let bundle = Bundle.main.bundleIdentifier {
            sharedPreference.removePersistentDomain(forName: bundle)
        }
    }
    
    //MARK:- setter methods.
       func saveUserToken (_ userToken : String) {
        sharedPreference.set(userToken, forKey: "userToken")
    }
    
    
  
    
    //MARK:- getter Methods.
    
    func getUserToken() -> String? {
        return sharedPreference.value(forKey: "userToken") as? String
    }

ViewController.swift

import UIKit

class ViewController: UIViewController {  
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        let token = "ABCDEFGD!@#$456MK"
        SharedPreferenceManager.sharedIntance.saveUserToken(token)
        
        if let token = SharedPreferenceManager.sharedIntance.getUserToken(){
            debugPrint(token)
        }
     }
    }

The SharedPreferenceManager class can be used in a real-time project where we can put all the setter and getter methods to save and retrieve values from UserDefaults.

Where to use UserDefaults

The UserDefaults are mainly used to store simple pieces of data. However, If we need to store multiple objects of the same type, it's better to use an actual database, like CoreData or SQLite. Database design is an important aspect of the architecture of your app. We will learn CoreData in the next section of this tutorial.

Use Cases of using UserDefaults

We can store user information like name, email address, age, or occupation in UserDefaults.
We can store the navigation flags which can be checked in AppDelegate, and the user is navigated based upon the flags saved in UserDefaults.
Application Settings like interface language, color theme, etc. can be stored in UserDefaults.
We can store the user access token in the UserDefaults.

Next TopicCoreData

← prev next →