My research on UserDefaults. User defaults can be used for saving types such as: Bool, Dictionary, Int, String, Data, Array
I made this library to make user-default simpler: https://github.com/eonist/UserDefaultSugar
Example
// variables
let defaults = UserDefaults.standard
defaults.set(25, forKey: "Age")
defaults.set(true, forKey: "hasOnboarded")
defaults.set(CGFloat.pi, forKey: "Pi")
defaults.set("Paul Hudson", forKey: "Name")
defaults.set(Date(), forKey: "LastRun")
// Arr and dict:
let array = ["Hello", "World"]
defaults.set(array, forKey: "SavedArray")
let dict = ["Name": "Paul", "Country": "UK"]
defaults.set(dict, forKey: "SavedDict")
Reading object
UserDefaults.standard.set("John", forKey: "FirstName")
print(UserDefaults.standard.object(forKey: "FirstName"))//John
Remove object
UserDefaults.standard.set(25, forKey: "Age")
print(UserDefaults.standard.object(forKey: "Age"))//25
UserDefaults.standard.removeObject(forKey: "Age")
print(UserDefaults.standard.object(forKey: "Age"))//nil
Unwrap object
let array = defaults.object(forKey:"SavedArray") as? [String] ?? [String]()
let dict = defaults.object(forKey: "SavedDict") as? [String: String] ?? [String: String]()
String
UserDefaults.standard.set("John", forKey: "name")
//Retrieving String
let name = UserDefaults.standard.string(forKey: “name”) ?? “”
Bool
//Saving Boolean value
UserDefaults.standard.set(true, forKey: “userlogin”)
//Retrieving Boolean value
let status = UserDefaults.standard.bool(forKey: “userlogin”) ?? false
The model approach
import Foundation
/**
* Persistent storage for prefrences
* ## Examples:
* Defaults.nameAndAddress = (name: "John", address: "New York") // Saving details
* let name = Defaults.nameAndAddress.name // Retrieving details
* Defaults.clearUserData() // Clear details
*/
struct Storage {
/**
* - Fixme: ⚠️️ this should be try error etc ⚠️
*/
static var nameAndAddress: NameAndAddress {
get { // Returns the Dictionary for the userSessionKey
let model: Model = {
if let dict: [String: String] = (UserDefaults.standard.value(forKey: userSessionKey) as? [String: String]) {
return Model(dict) // Convert dictionary to model
} else {
return defaultModel
}
}()
return (model.name ?? "err", model.address ?? "err") // Convert model to tuple and return it
}
set { // Stores the Dictionary for the userSessionKey
UserDefaults.standard.set([nameKey: newValue.name, addressKey: newValue.address], forKey: userSessionKey)
}
}
/**
* Removes the dictionary with the userSessionKey
*/
static func clearUserData() {
UserDefaults.standard.removeObject(forKey: userSessionKey)
}
}
/**
* TypeAlias
*/
extension Storage {
typealias NameAndAddress = (name: String, address: String)
}
/**
* Constants
*/
extension Storage {
/**
* The keys that is used in the dictionary (Dictionary is stored in the UserDefaults.standard only)
*/
static let (nameKey, addressKey) = ("name", "address")
/**
* This is the unique key that ensures that no other part of the app overwrites this (key,value) pair in the user-defaults file
*/
static let userSessionKey = "io.github.futurelab.\("UUID")" // add user uuid here
/**
* Default model if none is set yet
*/
static var defaultModel: Model = {
let name: String = "Adam"
let address: String = "Boston"
return .init([nameKey: name, addressKey: address])
}()
}
/**
* Model
*/
extension Storage {
struct Model {
var name: String?
var address: String?
init(_ dict: [String: String]) {
self.name = dict[nameKey]
self.address = dict[addressKey]
}
}
}
Interacting with the Model:
Defaults.nameAndAddress = (name: "John", address: "New York") // Saving details
let name = Defaults.nameAndAddress.name // Retrieving details
Defaults.clearUserData() // Clear details
Extension example
extension UserDefaults {
/**
* ## Examples:
* UserDefaults.name
*/
class var name: String? {
get { return standard.string(forKey: "name") }
set { standard.set(newValue, forKey: "name") }
}
}
extension UserDefaults {
/**
* ## Examples:
* UserDefaults.stringDateDictionary
*/
class var stringDateDictionary: [String: Date]? {
get { return standard.object(forKey: "stringDateDictionary") as? [String:Date] }
set { standard.set(newValue, forKey: "stringDateDictionary") }
}
}
Other supported types are
stringArray(forKey: String) -> [String]?// Returns the array of strings associated with the specified key.data(forKey: String) -> Data?url(forKey: String) -> URL?//Returns the URL associated with the specified key.object(forKey: String) -> Any?👈 ✨//Returns the object associated with the specified key.integer(forKey: String) -> Int//Returns the integer value associated with the specified key.float(forKey: String) -> Float//Returns the float value associated with the specified key.double(forKey: String) -> Double//Returns the double value associated with the specified key.dictionaryRepresentation() -> [String : Any]//Returns a dictionary that contains a union of all key-value pairs in the domains in the search list.
Important
- integer, double, returns
0 - bool returns
false
Extra
didChangeNotification// allows you to get notifications when there is a change in the data of the userDefaults (only for the thread you currently operate at)- Create a custom UserDefault instance:
init?(suiteName: String?)//Creates a user defaults object initialized with the defaults for the specified database name.func addSuite(named: String)//Inserts the specified domain name into the receiver’s search list.func removeSuite(named: String)//Removes the specified domain name from the receiver’s search list.func register(defaults: [String : Any])//Adds the contents of the specified dictionary to the registration domain. (basically replace entire UserDefaults)
Resources
- Apple doc on UserDefaults: https://developer.apple.com/documentation/foundation/userdefaults
- My personal swift-tool-box press
Tand write userdefault.swift and you will find a small Extension https://github.com/eonist/swift-utils
Notes:
This is where the UserDeaults plist is stored: rootOfApplication/Library/Preferences/com.yourcompany.appName.plist