[shared_preferences] Variable binding in a condition requires an initializer fix (#4407)

Not sure that testing for this makes sense, unless we want to add old xcode versions to our test suite.

Let me know if I'm thinking about this incorrectly though.

fixes flutter/flutter#129983

Author: tarrinneal

packages/shared_preferences/shared_preferences_foundation/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.3.1
+
+* Fixes variable binding bug on older versions of Xcode.
+
 ## 2.3.0
 
 * Adds `clearWithParameters` and `getAllWithParameters` methods.

packages/shared_preferences/shared_preferences_foundation/darwin/Classes/SharedPreferencesPlugin.swift

@@ -55,7 +55,7 @@ public class SharedPreferencesPlugin: NSObject, FlutterPlugin, UserDefaultsApi {
   func getAllPrefs(prefix: String, allowList: [String]?) -> [String: Any] {
     var filteredPrefs: [String: Any] = [:]
     var allowSet: Set<String>?;
-    if let allowList {
+    if let allowList = allowList {
       allowSet = Set(allowList)
     }
     if let appDomain = Bundle.main.bundleIdentifier,

packages/shared_preferences/shared_preferences_foundation/pubspec.yaml

@@ -2,7 +2,7 @@ name: shared_preferences_foundation
 description: iOS and macOS implementation of the shared_preferences plugin.
 repository: https://github.com/flutter/packages/tree/main/packages/shared_preferences/shared_preferences_foundation
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+shared_preferences%22
-version: 2.3.0
+version: 2.3.1
 
 environment:
   sdk: ">=2.18.0 <4.0.0"