OpenObservation

Backport implementation of Swift's Observation framework with access to @_spi(SwiftUI) APIs.

CI Status

Purpose

The official Observation framework in Swift Toolchain doesn't ship with package.swiftinterface, preventing direct use of @_spi(SwiftUI) APIs. There are two solutions to this problem, but this project provides solution 2:

1. Manual workaround (not included): Construct a package.swiftinterface and add it to the toolchain (⚠️ No API stability, may break between toolchain versions)

2. OpenObservation approach (this project): Reimplement Observation framework, allowing OpenSwiftUI to import it via @_spi(OpenSwiftUI)

Implementation Status

The current implementation is aligned with Swift's release/6.1 branch implementation of the Observation framework.

Features

• Full Observation framework implementation
• Cross-platform support (macOS, iOS, tvOS, watchOS)
• @Observable macro support
• Thread-safe tracking
• Pure Swift fallback for platforms without toolchain support

Installation

dependencies: [
    .package(url: "https://github.com/OpenSwiftUIProject/OpenObservation", from: "1.0.0")
]

Documentation

Comprehensive documentation is available on Swift Package Index.

Usage

import OpenObservation

@Observable
class Counter {
    var value: Int = 0
    
    func increment() {
        value += 1
    }
}

// Use with ObservationTracking
let counter = Counter()
withObservationTracking {
    print("Counter value: \(counter.value)")
} onChange: {
    print("Counter changed!")
}

Configuration

• OPENSWIFTUI_SWIFT_TOOLCHAIN_SUPPORTED: Enable Swift toolchain runtime implementation (auto-detected)
  • Config OPENSWIFTUI_SWIFT_TOOLCHAIN_PATH and OPENSWIFTUI_SWIFT_TOOLCHAIN_VERSION
• OPENOBSERVATION_DEVELOPMENT: Development mode

License

• OpenObservation code: MIT License
• Code derived from Swift project: Apache License v2.0 with Runtime Library Exception

See LICENSE file.