Update Discarded Notification Center Observer Violation false positive trigger on array append

CHANGELOG.md

@@ -31,6 +31,11 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#2628](https://github.com/realm/SwiftLint/issues/2628)
 
+* `discarded_notification_center_observer` rule now checks if the observer is
+  added to any collection or passed to a function before triggering the violation.  
+  [jsloop42](https://github.com/jsloop42)
+  [#2684](https://github.com/realm/SwiftLint/issues/2684)
+
 ## 0.31.0: Busy Laundromat
 
 #### Breaking

Rules.md

@@ -3078,6 +3078,32 @@ func foo() -> Any {
 
 ```
 
+```swift
+var obs: [Any?] = []
+obs.append(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))
+
+```
+
+```swift
+var obs: [String: Any?] = []
+obs["foo"] = nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })
+
+```
+
+```swift
+var obs: [Any?] = []
+obs.append(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))
+
+```
+
+```swift
+func foo(_ notif: Any) {
+   obs.append(notif)
+}
+foo(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))
+
+```
+
 </details>
 <details>
 <summary>Triggering Examples</summary>

Source/SwiftLintFramework/Rules/Lint/DiscardedNotificationCenterObserverRule.swift

@@ -17,7 +17,17 @@ public struct DiscardedNotificationCenterObserverRule: ASTRule, ConfigurationPro
             "let foo = nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n",
             "func foo() -> Any {\n" +
             "   return nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n" +
-            "}\n"
+            "}\n",
+            "var obs: [Any?] = []\n" +
+            "obs.append(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))\n",
+            "var obs: [String: Any?] = []\n" +
+            "obs[\"foo\"] = nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n",
+            "var obs: [Any?] = []\n" +
+            "obs.append(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))\n",
+            "func foo(_ notif: Any) {\n" +
+            "   obs.append(notif)\n" +
+            "}\n" +
+            "foo(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))\n"
         ],
         triggeringExamples: [
             "↓nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil) { }\n",
@@ -51,6 +61,11 @@ public struct DiscardedNotificationCenterObserverRule: ASTRule, ConfigurationPro
                 return []
         }
 
+        if let lastMatch = regex("\\b[^\\(]+").matches(in: file.contents, options: [], range: range).last?.range,
+            lastMatch.location == range.length - lastMatch.length - 1 {
+            return []
+        }
+
         if let lastMatch = regex("\\s?=\\s*").matches(in: file.contents, options: [], range: range).last?.range,
             lastMatch.location == range.length - lastMatch.length {
             return []