Support explicit animations in SwiftUI (#52)

* Support for explicit animations.

* wip

* wip

* wip

* Update Package.swift

---------

Co-authored-by: Stephen Celis <stephen@stephencelis.com>

Example/Example/ContentView.swift

@@ -8,10 +8,14 @@ class CounterModel {
   var isPresentingSheet = false
   var text = ""
   func decrementButtonTapped() {
-    count -= 1
+    withAnimation {
+      count -= 1
+    }
   }
   func incrementButtonTapped() {
-    count += 1
+    withAnimation {
+      count += 1
+    }
   }
   func presentSheetButtonTapped() {
     isPresentingSheet = true
@@ -28,8 +32,10 @@ struct ContentView: View {
         TextField("Text", text: $model.text)
         if model.isDisplayingCount {
           Text(model.count.description)
+            .font(.largeTitle)
         } else {
           Text("Not tracking count")
+            .font(.largeTitle)
         }
         Button("Decrement") { model.decrementButtonTapped() }
         Button("Increment") { model.incrementButtonTapped() }
@@ -45,6 +51,7 @@ struct ContentView: View {
           WithPerceptionTracking {
             Form {
               Text(model.count.description)
+                .font(.largeTitle)
               Button("Decrement") { model.decrementButtonTapped() }
               Button("Increment") { model.incrementButtonTapped() }
             }

Package.swift

@@ -47,3 +47,15 @@ let package = Package(
     ),
   ]
 )
+
+//for target in package.targets where target.type != .system {
+//  target.swiftSettings = target.swiftSettings ?? []
+//  target.swiftSettings?.append(
+//    .unsafeFlags([
+//      "-c", "release",
+//      "-emit-module-interface", "-enable-library-evolution",
+//      "-Xfrontend", "-warn-concurrency",
+//      "-Xfrontend", "-enable-actor-data-race-checks",
+//    ])
+//  )
+//}

Sources/Perception/WithPerceptionTracking.swift

@@ -42,7 +42,6 @@ import SwiftUI
 @available(macOS, deprecated: 14, message: "Remove WithPerceptionTracking")
 @available(tvOS, deprecated: 17, message: "Remove WithPerceptionTracking")
 @available(watchOS, deprecated: 10, message: "Remove WithPerceptionTracking")
-@MainActor
 public struct WithPerceptionTracking<Content> {
   @State var id = 0
   let content: () -> Content
@@ -55,10 +54,8 @@ public struct WithPerceptionTracking<Content> {
       let _ = self.id
       return withPerceptionTracking {
         self.instrumentedBody()
-      } onChange: {
-        Task { @MainActor in
-          self.id += 1
-        }
+      } onChange: { [_id = UncheckedSendable(self._id)] in
+        _id.value.wrappedValue += 1
       }
     }
   }
@@ -167,3 +164,10 @@ public enum _PerceptionLocals {
   @TaskLocal public static var isInPerceptionTracking = false
   @TaskLocal public static var skipPerceptionChecking = false
 }
+
+private struct UncheckedSendable<A>: @unchecked Sendable {
+  let value: A
+  init(_ value: A) {
+    self.value = value
+  }
+}