BYOD: Bring Your Own Database And More

This update's a big one!

This version update isn't just one version update, it's two. Boutique's 2.0 depends on Bodega version 2.0, which is a huge update in its own right. The Bring Your Own Database feature is powered by Bodega, which means you get all of the functionality with no API changes to Boutique. And of course it's still only a couple of lines of code to have an app with a single source of truth, realtime updates, the offline support you've come to know and love, and now 5-10x faster out of the box.

But before we talk about the database, let's see what else Boutique 2.0 has to offer.

Warning This version contains breaking changes

`@StoredValue`

Most data your app works with is in the shape of an array, but sometimes you need to store a single value. That's what @StoredValue is for. As the name implies @StoredValue allows you to store a value, which is great for saving user preferences, configurations, or even individual value like lastOpenedDate.

Creating a @StoredValue is easy, it even supports default values like you would expect with any other Swift property.

@StoredValue<RedPanda>(key: "pandaRojo")
private var spanishRedPanda = RedPanda(cuteRating: 100)

A more complex example may look like this, for example if you were building a Youtube-like video app.

struct UserPreferences: Codable, Equatable {
    var hasProvidedNotificationsAccess: Bool
    var hasHapticsEnabled: Bool
    var prefersDarkMode: Bool
    var prefersWideScreenVideos: Bool
    var spatialAudioEnabled: Bool
}

struct UserPreferences: Codable, Equatable {
    var hasProvidedNotificationsAccess: Bool
    var hasHapticsEnabled: Bool
    var prefersDarkMode: Bool
    var prefersWideScreenVideos: Bool
    var spatialAudioEnabled: Bool
}

struct LikedVideos: Codable, Equatable {
    let ids: [Int]
}

struct DownloadedVideos: Codable, Equatable {
    let ids: [Int]
}

struct AppState {

    @StoredValue<UserPreferences>(key: "userPreferences")
    var preferences

    @StoredValue(key: "likedEpisodes")
    var likedVideos = LikedVideos(ids: [1, 2, 3])

    @StoredValue<DownloadedVideos>(key: "downloadedVideos")
    var downloadedVideos

    @StoredValue(key: "openLinksInSafari")
    var openLinksInSafari = true

}

Thank you to @iankeen for helping me iterate on @StoredValue, and working through some nuances as the final version took shape.

AppKit/UIKit support

This one does what it says on the tin, Boutique is no longer constrained to SwiftUI. @Stored and the new @StoredValue will work in UIKit and AppKit apps!

Chained Operations

This is a breaking change, but a very worthwhile one. Previously when you added an item there was an removingExistingItems parameter that would provide a form of cache invalidation. But as they say, the two hardest problems in computer science are naming, cache invalidation, and off by one errors, so let's fix all three in one fell swoop.

What used to look like this

public func add(_ item: Item, removingExistingItems existingItemsStrategy: ItemRemovalStrategy<Item>? = nil) async throws

Now becomes much simpler

public func add(_ item: Item) async throws -> Operation

The reason for the removingExistingItems parameter was to remove cached items and add new items in one operation, preventing multiple dispatches to the @MainActor. We wanted to avoid multiple dispatches to avoid multiple SwiftUI render cycles, and now we can avoid that thanks to Operation chaining. But what is Operation? An Operation is a type you never have to think about, but it allows us to chain commands together transparently, like this.

self.store.removeAll().add(items: [1, 2, 3]).run() // The Store now contains [1, 2, 3]
self.store.remove(1).add(items: [4, 5, 6]).run() // The Store now contains [2, 3, 4, 5, 6]

This fluent syntax is much more intuitive, and no longer do you have a confusing parameter that conflates cache invalidation and adding items due to an unexpected side effect of how SwiftUI renders occur.

Thank you to @davedelong for helping me think through and prototyping chained operations, I really appreciate what came to be and wouldn't have gotten there without his help.

defaultStorageDirectory

Previously the default folder location a Store was initialized was the Documents directory. This makes sense on iOS, tvOS, and more locked down platforms, but on macOS it makes more sense to store data in the Application Support folder. Support for defaultStorageDirectory comes from Bodega, but if you're initializing a Boutique Store the location will now default to the expected folder on each platform.

Bring Your Own Database

In the Version 1.x series of Bodega the DiskStorage type was responsible for persisting data to disk. As the name implies DiskStorage was backed by the file system, but what if you don't want to save Data to disk? Saving data to disk is a simple and effective starting point, but can get slow when working with large data sets. One of Bodega's goals is to work with every app without causing developers to make tradeoffs, so version 2.0 is focused on eliminating those tradeoffs without ruining the streamlined simplicity Bodega brings, and brings that to Boutique.

In the spirit of not making tradeoffs here's how Bodega works with any database you want, say hello to the new StorageEngine protocol.

public protocol StorageEngine: Actor {
    func write(_ data: Data, key: CacheKey) async throws
    func write(_ dataAndKeys: [(key: CacheKey, data: Data)]) async throws

    func read(key: CacheKey) async -> Data?
    func read(keys: [CacheKey]) async -> [Data]
    func readDataAndKeys(keys: [CacheKey]) async -> [(key: CacheKey, data: Data)]
    func readAllData() async -> [Data]
    func readAllDataAndKeys() async -> [(key: CacheKey, data: Data)]

    func remove(key: CacheKey) async throws
    func remove(keys: [CacheKey]) async throws
    func removeAllData() async throws

    func keyExists(_ key: CacheKey) async -> Bool
    func keyCount() async -> Int
    func allKeys() async -> [CacheKey]

    func createdAt(key: CacheKey) async -> Date?
    func updatedAt(key: CacheKey) async -> Date?
}

By providing your own write, read, remove, key, and timestamp related functions, you can make any persistence layer compatible with ObjectStorage. Whether your app is backed by Realm, Core Data, or even CloudKit, when you create a new StorageEngine it automatically becomes usable by ObjectStorage, with one drop dead simple API.

The first StorageEngine to be implemented is an SQLiteStorageEngine, bundled with Bodega. I'll explain all the possibilities below, but first let's take a second to see how much faster your apps using Bodega and Boutique will be.

StorageEngine Read Performance StorageEngine Write Performance

If it's not obvious, a SQLite foundation for Bodega is incredibly faster than using the file system. The DiskStorageStorageEngine is still available, but if you use the SQLiteStorageEngine loading 10,000 objects into memory will be more than 400% faster, and writing 5,000 objects is more than 500% faster. With this release I feel confident that you should be able to use Bodega and Boutique in the largest of apps, while counterintuitively becoming a more flexible framework.

Breaking

Now that you can provide a StorageEngine the Store initializer goes from this

let animalsStore = Store<Animal>(
        storagePath: Store<Animal>.documentsDirectory(appendingPath: "Animals"),
        cacheIdentifier: \.id
    )

To this

let animalsStore = Store<Animal>(
    storage: SQLiteStorageEngine(directory: .defaultStorageDirectory(appendingPath: "Animals")),
    cacheIdentifier: \.id
)

Or even simpler if you use the new default SQLiteStorageEngine in the default Data database.

let animalsStore = Store<Animal>(cacheIdentifier: \.id)

For a backwards compatible StorageEngine you can use the new DiskStorageEngine, which was powering your data in v1.

let animalsStore = Store<Animal>(
    storage: DiskStorageEngine(directory: .defaultStorageDirectory(appendingPath: "Animals")),
    cacheIdentifier: \.id
)

P.S. If you build something useful to others, by all means file a pull request so I can add it to Boutique!

mergesort / Boutique