Working with Data Persistence

let defaults = UserDefaults.standard

// Saving data
defaults.set("John Doe", forKey: "username")
defaults.set(25, forKey: "age")
defaults.set(true, forKey: "isSubscribed")

// Retrieving data
let username = defaults.string(forKey: "username")
let age = defaults.integer(forKey: "age")
let isSubscribed = defaults.bool(forKey: "isSubscribed")

let defaults = UserDefaults.standard

// Saving arrays and dictionaries
let hobbies = ["reading", "swimming", "coding"]
let userPreferences = [
    "theme": "dark",
    "notifications": true
]

defaults.set(hobbies, forKey: "hobbies")
defaults.set(userPreferences, forKey: "preferences")

// Retrieving arrays and dictionaries
let savedHobbies = defaults.array(forKey: "hobbies") as? [String]
let savedPreferences = defaults.dictionary(forKey: "preferences") as? [String: Any]

import Foundation

let fileManager = FileManager.default
guard let documentsDirectory = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first else {
    print("Could not access documents directory")
    return
}

let fileURL = documentsDirectory.appendingPathComponent("data.json")
let data = "Hello, World!".data(using: .utf8)!

do {
    try data.write(to: fileURL)
    print("Data written to \(fileURL)")
} catch {
    print("Failed to write data: \(error)")
}

import Foundation

let fileManager = FileManager.default
guard let documentsDirectory = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first else {
    print("Could not access documents directory")
    return
}

let fileURL = documentsDirectory.appendingPathComponent("data.json")

do {
    let data = try Data(contentsOf: fileURL)
    let string = String(data: data, encoding: .utf8)
    print("Read data: \(string ?? "Empty")")
} catch {
    print("Failed to read data: \(error)")
}

import Foundation

let text = "Hello, World!"
let fileName = "example.txt"

// Get the documents directory URL
guard let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else {
    fatalError("Unable to access documents directory")
}

// Create the file URL
let fileURL = documentsDirectory.appendingPathComponent(fileName)

// Write text to file
do {
    try text.write(to: fileURL, atomically: true, encoding: .utf8)
    print("File written successfully to \(fileURL.path)")
} catch {
    print("Failed to write file: \(error)")
}

import Foundation

struct User: Codable {
    let name: String
    let email: String
}

let user = User(name: "John Doe", email: "john@example.com")

let encoder = JSONEncoder()
if let data = try? encoder.encode(user) {
    let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("user.json")
    try? data.write(to: url)
}

import Foundation

struct User: Codable {
    let name: String
    let email: String
}

let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("user.json")

if let data = try? Data(contentsOf: url),
   let user = try? JSONDecoder().decode(User.self, from: data) {
    print("Loaded user: \"\(user.name)\"")
}

import Foundation

let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
let libraryPath = NSSearchPathForDirectoriesInDomains(.libraryDirectory, .userDomainMask, true)[0]
let tmpPath = NSTemporaryDirectory()

print("Documents Path: \(documentsPath)")
print("Library Path: \(libraryPath)")
print("Temporary Path: \(tmpPath)")

import Security

let password = "mySecretPassword"
let service = "MyAppService"
let account = "user@example.com"

let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: service,
    kSecAttrAccount as String: account,
    kSecValueData as String: password.data(using: .utf8)!
]

let status = SecItemAdd(query as CFDictionary, nil)
if status == errSecSuccess {
    print("Password stored successfully")
} else {
    print("Failed to store password: \(status)")
}

import Security

let service = "MyAppService"
let account = "user@example.com"

let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: service,
    kSecAttrAccount as String: account,
    kSecReturnData as String: true,
    kSecMatchLimit as String: kSecMatchLimitOne
]

var result: AnyObject?
let status = SecItemCopyMatching(query as CFDictionary, &result)

if status == errSecSuccess {
    if let data = result as? Data,
       let password = String(data: data, encoding: .utf8) {
        print("Retrieved password: \(password)")
    }
} else {
    print("Failed to retrieve password: \(status)")
}

let mappingModel = NSMappingModel.from(
    sourceModel: oldModel,
    destinationModel: newModel
)
let migrationManager = NSMigrationManager(sourceModel: oldModel, destinationModel: newModel)
try migrationManager.migrateStore(
    from: storeURL,
    sourceType: NSSQLiteStoreType,
    to: newStoreURL,
    destinationType: NSSQLiteStoreType,
    options: nil
)

import Foundation

let userDefaults = UserDefaults.standard
userDefaults.set("John Doe", forKey: "username")
userDefaults.set(25, forKey: "age")
userDefaults.synchronize()