Introducing EasyStash — Easy data persistence in Swift

Khoa Pham
Khoa Pham
Jun 12, 2019 · 2 min read

The library is available on CocoaPods

EasyStash is an easy and lightweight persistence framework in Swift. With simple abstraction over NSCache and FileManager, it saves us from tedious work of saving and loading objects. There are no clever async, expiry handling or caching strategy for now, just save and load.

  • [x] Swift 5
  • [x] Support iOS, macOS, tvOS
  • [x] Synchronous APIs with explicit try catch
  • [x] Persist UIImage/NSImage
  • [x] Persist Codable objects, including primitive types
  • [x] Persist Data
  • [x] Test coverage


The main and only class is Storage which encapsulates memory and disk cache. All operations involving disk are error prone, we need to handle error explicitly.

With Options, we can customize folder name, searchPathDirectory, encoder and decoder for Codable

let options = Options()
options.folder = "Users"
storage = try! Storage(options: options)
try, forKey: "image")
try, forKey: "codable")

Memory cache is checked first before doing disk operations, so we won’t hit disk that often.

Saving and loading images

Works for both UIImage and NSImage. Because image and data loading uses the same signatures, we need to explicitly specify type

try, forKey: "image")
let loadedImage: UIImage = try storage.load(forKey: "image")

Saving and loading Codable objects

Uses JSONEncoder and JSONDecoder under the hood to serialize and deserialize to and from Data

let user = User(name: "A", age: 10)
let cities = [City(name: "Oslo"), City(name: "New York")]
try, forKey: "user")
try, forKey: "cities")
let loadedUser = try storage.load(forKey: "user", as: User.self)
let loadedCities = try storage.load(forKey: "cities", as: [City].self)

Saving and loading Data

try data, forKey: "data")
let loadedData: Data = try storage.load(forKey: "data")

Saving and loading primitives

Although primitives like Int, String, Bool conform to Codable, they can't be serialized into Data using JSONEncoder because json needs root object. This framework handles this case, so you can just save and load as normal

try, forKey: "an int")
try, forKey: "a boolean")

Folder informations

EasyStash includes some helpful functions to check file and folder within its Storage.

Check if file exists

try storage.exists(forKey: "has_updated_profile")

Remove file

try storage.remove(forKey: "a flag")

Remove all files

try storage.removeAll()

List all files. Each file has name, url, modificationDate and sizeinformation

let files = try storage.files()

Check folder size

let size = try storage.folderSize()

Check if folder has content

try storage.isEmpty()

Remove files based on predicate. This is useful when we want to clear expired objects, or objects based certain criteria.

try storage.removeAll(predicate: { $0.modificationDate < migrationDate })


EasyStash is designed to be synchronous. If we want to do async, it's easy as using DispatchQueue {
do {
try, forKey: "large_image")
} catch {


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Khoa Pham

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Khoa Pham

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Simple apps that make sense

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