codable-data-manager

A lightweight file/data manager that handles reading and writing Swift Codable objects from/to disk.

Installation

Add the following as a package in your Package.swift file or Xcode project:

git@github.com:rlziii/codable-data-manager.git

Then simply import CodableDataManager where needed.

Usage

In the most simple case a new DataManager() object can be created that uses FileManager.default and an app's document directory. For more specialized use cases (e.g. to use a different directory or for testing setups), a DataManager can be created with a custom DataFileManager. To do so, create a new DataFileManager and override the necessary closures. Alternatively, an extension on DataFileManager can be created with a new static property definition (e.g. DataFileManager+Default.swift) to improve the ergonomics (allowing for an initialization such as DataManager(.test)).

Once a DataManager has been created, there are two primary methods to use:

public func write<T: Encodable>(_ encodable: T, filename: String, shouldOverwrite: Bool = true) throws

Use this method to write new Encodable data to a specified filename location. Filenames should be unique in some way as (by default) they will be overwritten. If shouldOverwrite is set to false and a file already exists with the specified filename then a DataManagerError.fileExists error will be thrown.

public func read<T: Decodable>(_ type: T.Type, filename: String) throws -> T?

Use this method to read a previously-written file (via a known filename) back as a Decodable object (the type). The method returns an Optional in the case that the data is not found at the filename location (i.e. it does not exist). This method may also throw in the case where the data cannot be properly decoded (this is likely to be a DecodingError thrown from JSONDecoder).

A simple example use case may look like this:

struct GameInfo: Codable {
  let username: String
  let highScore: Int
}

...

class GameInfoManager {
  private let dataManager = DataManager()

  private var username = ""
  private var highScore = 0

  // ...

  func saveGameInfo() {
    let gameInfo = GameInfo(username: username, highScore: highScore)
    try? dataManager.write(gameInfo, filename: "game_info.json")
  }

  func loadGameInfo() -> GameInfo? {
    try? dataManager.read(GameInfo.self, filename: "game_info.json")
  }
}

License

MIT License. See LICENSE file for more details.