d

src/App.swift

@@ -18,8 +18,10 @@ class AppDelegate: UIResponder, UIApplicationDelegate
         window?.makeKeyAndVisible()
         
         
-        Bus.processSyncG(
-            MeetupId.shouldFormat, MeetupId.K.meetupIdTextUI.rawValue, MeetupId.K.meetupIdTextApp.rawValue
+        Bus.process(
+          MeetupId.K.meetupIdTextUI.rawValue,
+          MeetupId.K.meetupIdTextApp.rawValue,
+          MeetupId.shouldFormat
         )
 
         return true

src/Bus.swift

@@ -22,6 +22,20 @@ extension Bus {
   }
 }
 
+private extension Bus {
+  static func subscribe(
+    _ subscription: AnyCancellable?,
+    _ sub: UnsafeMutablePointer<[AnyCancellable]>?
+  ) {
+    guard let subscription else { return }
+    if let sub = sub {
+      sub.pointee.append(subscription)
+    } else {
+      Service.singleton.subscriptions.append(subscription)
+    }
+  }
+}
+
 public extension Bus {
   static func receive<T>(
     _ keys: Set<String>,
@@ -80,41 +94,32 @@ public extension Bus {
   }
 }
 
-private extension Bus {
-  static func subscribe(
-    _ subscription: AnyCancellable?,
-    _ sub: UnsafeMutablePointer<[AnyCancellable]>?
-  ) {
-    guard let subscription else { return }
-    if let sub = sub {
-      sub.pointee.append(subscription)
-    } else {
-      Service.singleton.subscriptions.append(subscription)
-    }
-  }
-}
-
 public extension Bus {
-  static func processSync<Src, Dst>(
-    _ subscriptions: inout [AnyCancellable],
-    _ handler: @escaping ((Src) -> Dst?),
+  static func process<Src, Dst>(
     _ keyIn: String,
-    _ keyOut: String
+    _ keyOut: String,
+    _ handler: @escaping ((Src) -> Dst?),
+    opt: [Option] = [],
+    sub: UnsafeMutablePointer<[AnyCancellable]>? = nil
   ) {
-    Service.singleton.events
-      .compactMap { processKeyValue($0, keyIn, handler) }
-      .sink { vOut in Service.singleton.send(keyOut, vOut) }
-      .store(in: &subscriptions)
-  }
+    var subscription: AnyCancellable?
+    let isAsync = opt.contains(.async)
 
-  static func processSyncG<Src, Dst>(
-    _ handler: @escaping ((Src) -> Dst?),
-    _ keyIn: String,
-    _ keyOut: String
-  ) {
-    Service.singleton.events
+    // Async.
+    if isAsync {
+      subscription = Service.singleton.events
+      .compactMap { processKeyValue($0, keyIn, handler) }
+      .receive(on: DispatchQueue.main)
+      .sink { vOut in Service.singleton.send(keyOut, vOut) }
+    }
+
+    // Sync.
+    if !isAsync {
+      subscription = Service.singleton.events
       .compactMap { processKeyValue($0, keyIn, handler) }
       .sink { vOut in Service.singleton.send(keyOut, vOut) }
-      .store(in: &Service.singleton.subscriptions)
+    }
+
+    subscribe(subscription, sub)
   }
 }