fix(apple): Use Task.detached when loading sysex and vpn config (#7815)

When the app starts, we perform various checks in the
`AppViewModel.init` which read and write to disk, which can potentially
be slow (a few seconds), especially for busy rotational hard drives.

These were performed inside a regular `Task` closure, but since
AppViewModel is annotated `@MainActor`, that meant this Task blocked the
main UI thread until the operations completed.

In practice this wasn't an issue because it simply manifested as the app
taking a couple seconds to launch under these conditions.

We fix this by simply using a `Task.detached` which will run the
operations on another thread. Now, the first window will pop up sooner
and immediately show the `ProgressView()` (i.e. a loading spinner icon)
until these operations complete.

A few minor reorganizing of the `os()` macro was also performed because
some of the variables now need to be `await`ed because they live on the
main thread.

refs #7798

swift/apple/FirezoneKit/Sources/FirezoneKit/Stores/Store.swift

@@ -115,11 +115,11 @@ public final class Store: ObservableObject {
     }
   }
 
-  func checkedIfInstalled() async throws {
 #if os(macOS)
+  func checkedSystemExtensionStatus() async throws -> SystemExtensionStatus {
     let checker = SystemExtensionManager()
 
-    self.systemExtensionStatus = try await withCheckedThrowingContinuation {
+    let status = try await withCheckedThrowingContinuation {
       (continuation: CheckedContinuation<SystemExtensionStatus, Error>) in
 
       checker.checkStatus(
@@ -130,14 +130,16 @@ public final class Store: ObservableObject {
 
     // If already installed but the wrong version, go ahead and install.
     // This shouldn't prompt the user.
-    if self.systemExtensionStatus == .needsReplacement {
+    if status == .needsReplacement {
       try await installSystemExtension()
     }
-#endif
+
+    self.systemExtensionStatus = status
+
+    return status
   }
 
   func installSystemExtension() async throws {
-#if os(macOS)
     let installer = SystemExtensionManager()
 
     // Apple recommends installing the system extension as early as possible after app launch.
@@ -150,8 +152,8 @@ public final class Store: ObservableObject {
         continuation: continuation
       )
     }
-#endif
   }
+#endif
 
   func grantVPNPermission() async throws {
     // Create a new VPN configuration in system settings.

swift/apple/FirezoneKit/Sources/FirezoneKit/Views/AppView.swift

@@ -32,27 +32,30 @@ public class AppViewModel: ObservableObject {
     self.favorites = favorites
     self.store = store
 
-    Task {
+    Task.detached { [weak self] in
+      guard let self else { return }
+
       do {
         try await self.store.bindToVPNConfigurationUpdates()
+        let vpnConfigurationStatus = await self.store.status
 
 #if os(macOS)
-        try await self.store.checkedIfInstalled()
-        let isInstalled = self.store.systemExtensionStatus == .installed
+        let systemExtensionStatus = try await self.store.checkedSystemExtensionStatus()
 
-        if !isInstalled || self.store.status == .invalid {
+        if systemExtensionStatus != .installed
+          || vpnConfigurationStatus == .invalid {
 
           // Show the main Window if VPN permission needs to be granted
-          AppViewModel.WindowDefinition.main.openWindow()
+          await AppViewModel.WindowDefinition.main.openWindow()
         } else {
-          AppViewModel.WindowDefinition.main.window()?.close()
+          await AppViewModel.WindowDefinition.main.window()?.close()
         }
 #endif
 
-        if self.store.status == .disconnected {
+        if vpnConfigurationStatus == .disconnected {
 
           // Try to connect on start
-          self.store.vpnConfigurationManager.start()
+          await self.store.vpnConfigurationManager.start()
         }
       } catch {
         Log.error(error)

swift/apple/FirezoneKit/Sources/FirezoneKit/Views/GrantVPNView.swift

@@ -27,21 +27,23 @@ final class GrantVPNViewModel: ObservableObject {
 #endif
   }
 
+#if os(macOS)
   func installSystemExtensionButtonTapped() {
     Task {
       do {
         try await store.installSystemExtension()
 
-#if os(macOS)
+
         // The window has a tendency to go to the background after installing
         // the system extension
         NSApp.activate(ignoringOtherApps: true)
-#endif
+
       } catch {
         Log.error(error)
       }
     }
   }
+#endif
 
   func grantPermissionButtonTapped() {
     Log.log("\(#function)")