Getting started

Put a value in the cache. Read it back with await.

Start with memory storage. Move to disk when an entry needs to survive beyond the cache actor.

Requirements

Swift 6.0 or later
macOS 15, iOS 17, tvOS 17, watchOS 10, or visionOS 1 or later

Install 1.1.0

Add SwiftStash to the package dependencies in Package.swift. Then add "SwiftStash" to the dependencies of your target.

Package.swift

.package(
    url: "https://github.com/modern-swift-dev/swift-stash.git",
    from: "1.1.0"
)

First cache entry

Cache is an actor. The cache accepts values that conform to Sendable. A string-backed enum gets the required CacheKey behavior automatically.

Swift

import SwiftStash

enum ProfileKey: String, CacheKey {
    case current
}

let storage = MemoryStorageEngine<ProfileKey, String>()
let cache = await Cache(storagePolicy: storage)

await cache.add("Ada", for: .current)
let currentProfile = await cache[.current]

Persist entries to disk

Create the named directory before persistence begins. DiskStorageEngine writes each entry below the app cache directory and does not create the named subdirectory for you.

Swift

let storage = DiskStorageEngine(
    directory: "profiles",
    keyType: ProfileKey.self,
    serializer: JsonDiskStorageSerializer<Profile>()
)
let cache = await Cache(storagePolicy: storage)

Compare cache state after eviction

Choose .fifo, .lifo, or .lru when creating the cache. Call evictExpired() to remove old entries, or call evictUntil(maxNbItems:) to first remove expired entries and then enforce a maximum count.

SwiftStash does not run a background timer. Place the eviction call in the workflow that knows when reducing the cache makes sense.

Cache state

Compare cache records before and after a count limit

Before

concurrencyA tour of Swift concurrency

actorsProtecting state with actors

2 entries

After evictUntil(maxNbItems: 1)

concurrencyA tour of Swift concurrency

1 entry