lynnswap/observationbridge

Use ObservationBridge to write continuous Observation callbacks with a portable

Requirements

Swift 6.3+
iOS 18.4+, Mac Catalyst 18.4+, macOS 15.4+, tvOS 18.4+, watchOS 11.4+, or visionOS 2.4+

Installation

Add https://github.com/lynnswap/ObservationBridge.git as a Swift Package Manager dependency and select the ObservationBridge product for your target.

Quick start

Call bindModel() when the view is ready. Read observable properties in the callback and retain the returned token for as long as you need updates. Runtime preparation happens automatically when needed:

import Observation
import ObservationBridge
import UIKit

@Observable
@MainActor
final class Counter {
    var count = 0
}

@MainActor
final class CounterViewController: UIViewController {
    let model = Counter()
    private var observation: PortableObservationTracking.Token?

    func bindModel() {
        observation = withPortableContinuousObservation { [weak self] _ in
            guard let self else { return }
            navigationItem.title = "Count: \(model.count)"
        }
    }
}

The callback runs initially, then again after the properties it reads change. Call observation?.cancel() to stop updates. Inspect observation?.error if startup or subsequent tracking fails.

You can optionally warm up the runtime during asynchronous application setup:

extension CounterViewController {
    func prepareAndBindModel() async throws {
        let preparation = Task.detached {
            try await PortableObservationTracking.prepare()
        }

        bindModel()
        try await preparation.value
    }
}

This method runs on MainActor, as does bindModel(). The observation can start before prepare() finishes. It reuses completed preparation and joins any running runtime work it needs. Synchronous startup can block the caller while searching or joining that work; asynchronous prepare() performs preparation away from MainActor.

Documentation

See DocC for API reference and detailed guides:

Package Metadata

Repository: lynnswap/observationbridge

Default branch: main

README: README.md