Update the template screen to use the new(ish) Observation framework. (#4077)

* Update the template screen to use the new(ish) Observation framework. * Add a variant of deferFulfillment that supports observables. * Update snapshot fulfilment to work with either a publisher or a stream.
2026-11-04 19:44:05 +00:00 · 2025-04-30 16:49:23 +01:00
parent 0620bd45fc
commit 61a427b8e5
12 changed files with 297 additions and 25 deletions
@@ -0,0 +1,37 @@
+//
+// Copyright 2025 New Vector Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Foundation
+
+extension Observable {
+    /// Creates an async stream for the specified property on this object. We probably won't need this once SE-0475 is available:
+    /// https://github.com/swiftlang/swift-evolution/blob/main/proposals/0475-observed.md
+    ///
+    /// - Parameter property: The key path to the property you would like to observe.
+    func observe<Value>(_ property: KeyPath<Self, Value>) -> AsyncStream<Value> {
+        AsyncStream { continuation in
+            var isActive = true
+            
+            @Sendable func observe() {
+                let value = withObservationTracking {
+                    self[keyPath: property]
+                } onChange: {
+                    // Dispatch the update as this is willSet not didSet.
+                    DispatchQueue.main.async {
+                        guard isActive else { return }
+                        observe()
+                    }
+                }
+                continuation.yield(value)
+            }
+            
+            continuation.onTermination = { _ in isActive = false }
+            
+            observe()
+        }
+    }
+}