Renamed StateProperty to ObservableProperty and make it public (#241)

* Renamed StateProperty to ObservableProperty and made the protocol public

* Implemented requested changes

moved ObservableProperty to separate file, updated documentation comment

* Attempt to fix CI run failing due to as? ObservableProperty instead of as? any ObservableProperty

Author: MiaKoring

Sources/SwiftCrossUI/State/ObservableProperty.swift

@@ -0,0 +1,11 @@
+import Foundation
+
+/// View properties that conform to ObservableProperty are automatically observed by SwiftCrossUI.
+///
+/// This protocol is intended to be implemented by property wrappers. You shouldn't
+/// have to implement it for your own model types.
+public protocol ObservableProperty: DynamicProperty {
+    var didChange: Publisher { get }
+    func tryRestoreFromSnapshot(_ snapshot: Data)
+    func snapshot() throws -> Data?
+}

Sources/SwiftCrossUI/State/State.swift

@@ -5,7 +5,7 @@ import Foundation
 // - It supports ObservableObject
 // - It supports Optional<ObservableObject>
 @propertyWrapper
-public struct State<Value>: DynamicProperty, StateProperty {
+public struct State<Value>: ObservableProperty {
     class Storage {
         // This inner box is what stays constant between view updates. The
         // outer box (Storage) is used so that we can assign this box to
@@ -55,7 +55,7 @@ public struct State<Value>: DynamicProperty, StateProperty {
 
     var storage: Storage
 
-    var didChange: Publisher {
+    public var didChange: Publisher {
         storage.box.didChange
     }
 
@@ -109,7 +109,7 @@ public struct State<Value>: DynamicProperty, StateProperty {
         }
     }
 
-    func tryRestoreFromSnapshot(_ snapshot: Data) {
+    public func tryRestoreFromSnapshot(_ snapshot: Data) {
         guard
             let decodable = Value.self as? Codable.Type,
             let state = try? JSONDecoder().decode(decodable, from: snapshot)
@@ -120,17 +120,11 @@ public struct State<Value>: DynamicProperty, StateProperty {
         storage.box.value = state as! Value
     }
 
-    func snapshot() throws -> Data? {
+    public func snapshot() throws -> Data? {
         if let value = storage.box as? Codable {
             return try JSONEncoder().encode(value)
         } else {
             return nil
         }
     }
 }
-
-protocol StateProperty {
-    var didChange: Publisher { get }
-    func tryRestoreFromSnapshot(_ snapshot: Data)
-    func snapshot() throws -> Data?
-}

Sources/SwiftCrossUI/ViewGraph/ViewGraphNode.swift

@@ -121,7 +121,7 @@ public class ViewGraphNode<NodeView: View, Backend: AppBackend>: Sendable {
                 )
             }
 
-            guard let value = property.value as? StateProperty else {
+            guard let value = property.value as? any ObservableProperty else {
                 continue
             }
 

Sources/SwiftCrossUI/ViewGraph/ViewGraphSnapshotter.swift

@@ -55,7 +55,7 @@ public struct ViewGraphSnapshotter: ErasedViewGraphNodeTransformer {
             let mirror = Mirror(reflecting: view)
             for property in mirror.children {
                 guard
-                    let stateProperty = property as? StateProperty,
+                    let stateProperty = property as? any ObservableProperty,
                     let propertyName = property.label,
                     let encodedState = state[propertyName]
                 else {
@@ -80,7 +80,7 @@ public struct ViewGraphSnapshotter: ErasedViewGraphNodeTransformer {
         for property in mirror.children {
             guard
                 let propertyName = property.label,
-                let property = property as? StateProperty,
+                let property = property as? any ObservableProperty,
                 let encodedState = try? property.snapshot()
             else {
                 continue

Sources/SwiftCrossUI/_App.swift

@@ -66,7 +66,7 @@ class _App<AppRoot: App> {
                     )
                 }
 
-                guard let value = property.value as? StateProperty else {
+                guard let value = property.value as? any ObservableProperty else {
                     continue
                 }