LSData is a lightweight framework that aims to completely abstract and generalise iOS model layer.

Concrete implementations, such as CoreData, UserDefaults, Keychain and networking layer are available in LSCocoa framework which are almost exclusively used together (unless you wish to write your own implementations).

The goal is to provide complex functionalities such as caching, syncing (i.e. syncing local database with backend), and refreshing, to any entities conforming to protocols in these frameworks. This would mean that all these functionalities are available out of the box.

Common use-cases (provided as basically one-liners to all classes conforming to these protocols):

• Sync your CoreData database with your backend database and vice-versa
• Cache, refresh and query your network requests
• Provide oAuth functionality with automatic refresh of tokens if needed on every request
• Redirect data flow to local if network is not available
• Many other, limited by your imagination :)

There are 3 main protocols in this framework explained below

Data Source

protocol DataSource {

    associatedtype Output    
    associatedtype Parameter = Void
    associatedtype OutputError: Error = Error

    func publisher(parameter: Parameter) -> AnyPublisher<Output, OutputError>
}

DataSource is a simple protocol used as a source of data. It uses Apple's Combine framework to provide reactivity. It is similar to Combine's Publisher except it can optionally be queried by Parameter.

Data Storage

protocol DataStorage {

    associatedtype StoredItem
    associatedtype StorageReturn = Void

    func store(_ item: StoredItem) -> StorageReturn
}

DataStorage is a protocol providing storage functionality (such as saving items to CoreData or to your network endpoint). StoredItem is often an array of elements (such as [User]).

Data Storage

protocol DeletableStorage {
    associatedtype DeletableItem
    associatedtype DeletionReturn = Void

    func delete(_ item: DeletableItem) -> DeletionReturn
    
    func deleteAll() -> DeletionReturn
}

DeletableStorage is a protocol provoding deletion functionality. Most concrete DataStorage (mentioned above) implementations might provide conform to DeletableStorage as well, having DeletableItem and StoredItem be the same type.