Add Async image loading

Examples/Time Travel/SwiftUITimeTravel/TimeTravelView/Store.swift

@@ -0,0 +1,44 @@
+import SwiftUI
+import Combine
+
+public final class Store<StateType>: BindableObject where StateType: StateMachine {
+    
+    private let initialState: StateType
+    private var subsequentStates: [StateType] = []
+
+    public let didChange = PassthroughSubject<Void, Never>()
+    
+    public init(state: StateType) {
+        initialState = state
+    }
+    
+    var allStates: [StateType] {
+        [[initialState], subsequentStates].flatMap({ $0 })
+    }
+    
+    var stateCount: Int {
+        1 + subsequentStates.count
+    }
+    
+    var currentStateIndex: Int = 0 {
+        didSet {
+            withAnimation {
+                didChange.send(())
+            }
+        }
+    }
+    
+    /// The current state of the store. This will update as time traveling occurs.
+    public var state: StateType {
+        allStates[currentStateIndex]
+    }
+    
+    /// Dispatches an event to be applied to the current state.
+    public func dispatch(event: StateType.Event) {
+        var newState = state
+        newState.update(with: event)
+        subsequentStates.append(newState)
+        currentStateIndex = stateCount - 1
+    }
+    
+}