Add back the removed "get" method so as not to break compatibility

Author: patrick-fu

ios/Classes/SharedPreferenceAppGroupPlugin.m

@@ -97,6 +97,14 @@ - (void)setStringArray:(FlutterMethodCall *)call result:(FlutterResult)result {
     result(nil);
 }
 
+- (void)get:(FlutterMethodCall *)call result:(FlutterResult)result {
+    [self checkAppGroup:result];
+
+    NSString *key = call.arguments[@"key"];
+    id value = [self.userDefaults valueForKey:key];
+    result(value);
+}
+
 - (void)getBool:(FlutterMethodCall *)call result:(FlutterResult)result {
     [self checkAppGroup:result];
 

lib/shared_preference_app_group.dart

@@ -48,6 +48,13 @@ class SharedPreferenceAppGroup {
     await _setValue('StringArray', key, value);
   }
 
+  /// Reads a value of any type from persistent storage under the specified app group.
+  ///
+  /// If the persistent storage does not contains [key], then [null] will be returned
+  static Future<dynamic> get(String key) async {
+    return await _channel.invokeMethod('get', {'key': key});
+  }
+
   /// Reads a boolean value from persistent storage under the specified app group.
   ///
   /// If the persistent storage does not contains [key], then [null] will be returned