CacheStore

SwiftUI Observable Cache

What is CacheStore?

CacheStore is a SwiftUI framework to help with state. Define keyed values that you can share locally or globally in your projects. CacheStore uses c, which a simple composition framework. c has the ability to create transformations that are either unidirectional or bidirectional. There is also a cache that values can be set and resolved, which is used in CacheStore.

Objects

• CacheStore: An object that needs defined Keys to get and set values.
• Store: An object that needs defined Keys, Actions, and Dependencies. (Preferred)

Store

A Store is an object that you send actions to and read state from. Stores use a private CacheStore to manage state behind the scenes. All state changes must be defined in a StoreActionHandler where the state gets modified depending on an action.

Basic Store Example

Here is a basic Store example where this is a Boolean variable called isOn. The only way you can modify that variable is be using defined actions for the given store. In this example there is only one action, toggle.

enum StoreKey {
    case isOn
}

enum Action {
    case toggle
}

let actionHandler = StoreActionHandler<StoreKey, Action, Void> { (store: inout CacheStore<StoreKey>, action: Action, _: Void) in
    switch action {
    case .toggle:
        store.update(.isOn, as: Bool.self, updater: { $0?.toggle() })
    }
}

let store = Store<StoreKey, Action, Void>(
    initialValues: [.isOn: false],
    actionHandler: actionHandler,
    dependency: ()
)

try t.assert(store.get(.isOn), isEqualTo: false)

store.handle(action: .toggle)

try t.assert(store.get(.isOn), isEqualTo: true)

Basic CacheStore Example

Here is a simple application that has two files, an App file and ContentView file. The App contains the StateObject CacheStore. It then adds the CacheStore to the global cache using c. ContentView can then resolve the cache as an ObservableObject which can read or write to the cache. The cache can be injected into the ContentView directly, see ContentView_Previews, or indirectly, see ContentView.

import c
import CacheStore
import SwiftUI

enum CacheKey: Hashable {
    case someValue
}

@main
struct DemoApp: App {
    @StateObject var cacheStore = CacheStore<CacheKey>(
        initialValues: [.someValue: "🥳"]
    )
    
    var body: some Scene {
        c.set(value: cacheStore, forKey: "CacheStore")
        
        return WindowGroup {
            VStack {
                Text("@StateObject value: \(cacheStore.resolve(.someValue) as String)")
                ContentView()
            }
        }
    }
}

ContentView

import c
import CacheStore
import SwiftUI

struct ContentView: View {
    @ObservedObject var cacheStore: CacheStore<CacheKey> = c.resolve("CacheStore")
    
    var stringValue: String {
        cacheStore.resolve(.someValue)
    }
    
    var body: some View {
        VStack {
            Text("Current Value: \(stringValue)")
            Button("Update Value") {
                cacheStore.set(value: ":D", forKey: .someValue)
            }
        }
        .padding()
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView(
            cacheStore: CacheStore(
                initialValues: [.someValue: "Preview Cache Value"]
            )
        )
    }
}