macsven/localstorage-swift

iOS, tvOS, watchOS storage for persisting small data sets

LocalStorage

Example

To run the example project, clone the repo and open Example/Example.xcodproj with Xcode 11+.

1. Choose a model to persist

/// Make model Codable to use default Decoder and Encoder
struct User: Codable {

    let name: String

    init(name: String) {
        self.name = name
    }
}

2. Create an LocalStorage.Manager instance and register storages

// Identifies existing Storages. Used internally for easy storage access through LocalStorage.Manager.
enum Identifier: String {
     case user

    // Path to store data to.
    var path: String {
      switch self {
        case .user: return "example.storage.user"
      }
    }
 }

// Storage persisting data to user storage to  key 'path'
let defaultsStorage = UserDefaultsStorage(userDefaults: UserDefaults.standard, path: Identifier.user.path)
// Wrap defaultsStorage with CachedStorage for faster access.
let userStorage = CachedStorage(storage: defaultsStorage)

// Dictionary containing all storages handled by Manager instance
let storages = [Identifier.user.rawValue: userStorage]

// DispatchLock to allow multiple reads but single write operations on storages. It will perform all
// operations on a concurrent DispatchQueue. It is also possible to simply use a NSLock, which may be
// easier to handle due to reduced thread states. On the downside NSLock has a lower performance on read
// operations than a DispatchLock.
let lock = DispatchLock(queue: DispatchQueue(label: "example.queue.storage", attributes: .concurrent))

// Serial queue for async handling. Enables sequential dispatching of completion blocks.
// Needed for required behaviour in example app.
// NOTE: Default Manager(storages: _, lock: _) uses a concurrent queue.
let asyncQueue = DispatchQueue(label: "async.queue")

let manager = Manager(storages: storages, lock: lock, asyncQueue: asyncQueue)

3. Save user

let user = User(name: "Bernd")
let encoder = FoundationEncoder<User>(encoder: JSONEncoder())
// Prefer async access over sync access
// Sync access := manager.append(_, using: _) -> Result<T, Error>
manager.async.append(user, to: Identifier.user.rawValue, using: encoder) { result in
    switch result {
    case .success(let savedUser):
        print("\(savedUser.name)")
    case .failure(let error):
        print(error)
    }
}

4. Load stored user list

let decoder = FoundationDecoder<User>(decoder: JSONDecoder())
// Prefer async access over sync access
// Sync access := manager.all(from: _, using: _) -> Result<[T], Error>
manager.async.all(from: Identifier.user.rawValue, using: decoder) { result in
   switch result {
   case .success(let user):
       user.forEach { print("\($0.name)") }
   case .failure(let error):
       print(error)
   }
}

Requirements

• Swift 5.0+
• iOS 11.0+
• tvOS 11.0+
• watchOS 5.0+

Installation

Swift Package Manager

  dependencies: [
        .package(url: "https://github.com/cellular/cellular-swift.git", from: "6.0.0")
    ]

CocoaPods

pod "CellularLocalStorage"

License

CellularLocalStorage is released under the MIT license. See LICENSE for details.