claybridges · March 24, 2020 20:28 · Mar 24, 2020
diff --git a/n10ns.md b/n10ns.md
@@ -0,0 +1,41 @@
+## Notification observations and handlers
+
+For a class, each notification observation should be handled by a single method. The name of that method should be `handle` appended with the name of the notification being observed. For instance, for notification name
+```
+NSNotification.Name.LUUICachedPaymentMethodDidUpdate
+```
+the handler would be
+```
+private func handleCachedPaymentMethodDidUpdate(...)
+```
+Skip whatever LU/LUUI prefixes exist.
+
+**Only the notification observation should call/reference the handler method.**
+
+Here's how the resultant code would look:
+```
+  // somewhere
+  NotificationCenter.default.addObserver(self, selector: #selector(handleCachedPaymentMethodDidUpdate),
+                                         name: NSNotification.Name.LUUICachedPaymentMethodDidUpdate,
+                                         object: nil)
+
+  // later
+  private func handleCachedPaymentMethodDidUpdate(_ notification: NSNotification) {
+     // 🧹 handle it! 
+  }
+
+```
+
+All notification handler methods should be private, and should be grouped together in a section delineated by
+```
+// MARK: - Notification handlers
+```
+
+## Motivation
+
+When trying to comprehend code, especially when debugging, it can become confusing to have a method that is called by:
+- multiple notifications
+- both by a notification and direct calls
+
+Breaking out notification handlers on their own is a simple, consistent way to structure this for clarity.
+