fix(ios): pass inputData to periodic background tasks

- Store inputData in UserDefaults when registering periodic tasks
- Retrieve and pass stored inputData when executing periodic tasks
- Fix issue where periodic tasks received nil inputData instead of provided data
- Update documentation with periodic task inputData examples

Closes #612

Author: ened

docs/quickstart.mdx

@@ -176,6 +176,19 @@ Workmanager().registerPeriodicTask(
   "cleanup",
   frequency: Duration(hours: 24),
 );
+
+// Schedule a periodic task with input data
+Workmanager().registerPeriodicTask(
+  "sync-task",
+  "data_sync",
+  frequency: Duration(hours: 6),
+  inputData: <String, dynamic>{
+    'server_url': 'https://api.example.com',
+    'sync_type': 'full',
+    'max_retries': 3,
+  },
+);
+```
 ```
 
 ## Task Results
@@ -200,4 +213,4 @@ Your background tasks can return:
 
 - **[Task Customization](customization)** - Advanced configuration with constraints, input data, and management
 - **[Debugging Guide](debugging)** - Learn how to debug and troubleshoot background tasks  
-- **[Example App](https://github.com/fluttercommunity/flutter_workmanager/tree/main/example)** - Complete working demo
+- **[Example App](https://github.com/fluttercommunity/flutter_workmanager/tree/main/example)** - Complete working demo

example/ios/Podfile.lock

@@ -38,7 +38,7 @@ EXTERNAL SOURCES:
 SPEC CHECKSUMS:
   Flutter: e0871f40cf51350855a761d2e70bf5af5b9b5de7
   integration_test: 4a889634ef21a45d28d50d622cf412dc6d9f586e
-  path_provider_foundation: 608fcb11be570ce83519b076ab6a1fffe2474f05
+  path_provider_foundation: 080d55be775b7414fd5a5ef3ac137b97b097e564
   permission_handler_apple: 4ed2196e43d0651e8ff7ca3483a069d469701f2d
   shared_preferences_foundation: 9e1978ff2562383bd5676f64ec4e9aa8fa06a6f7
   workmanager_apple: 904529ae31e97fc5be632cf628507652294a0778

workmanager_apple/ios/Sources/workmanager_apple/UserDefaultsHelper.swift

@@ -15,9 +15,15 @@ struct UserDefaultsHelper {
 
     enum Key {
         case callbackHandle
+        case periodicTaskInputData(taskIdentifier: String)
 
         var stringValue: String {
-            return "\(WorkmanagerPlugin.identifier).\(self)"
+            switch self {
+            case .callbackHandle:
+                return "\(WorkmanagerPlugin.identifier).callbackHandle"
+            case .periodicTaskInputData(let taskIdentifier):
+                return "\(WorkmanagerPlugin.identifier).periodicTaskInputData.\(taskIdentifier)"
+            }
         }
     }
 
@@ -31,6 +37,16 @@ struct UserDefaultsHelper {
         return getValue(for: .callbackHandle)
     }
 
+    // MARK: periodicTaskInputData
+
+    static func storePeriodicTaskInputData(_ inputData: [String: Any]?, forTaskIdentifier taskIdentifier: String) {
+        store(inputData, key: .periodicTaskInputData(taskIdentifier: taskIdentifier))
+    }
+
+    static func getStoredPeriodicTaskInputData(forTaskIdentifier taskIdentifier: String) -> [String: Any]? {
+        return getValue(for: .periodicTaskInputData(taskIdentifier: taskIdentifier))
+    }
+
     // MARK: Private helper functions
 
     private static func store<T>(_ value: T, key: Key) {

workmanager_apple/ios/Sources/workmanager_apple/WorkmanagerPlugin.swift

@@ -32,22 +32,31 @@ public class WorkmanagerPlugin: FlutterPluginAppLifeCycleDelegate, FlutterPlugin
         operationQueue.addOperation(operation)
     }
 
+    /// Handles execution of a periodic background task.
+    ///
+    /// This method is called by iOS when a BGAppRefreshTask is triggered.
+    /// It retrieves stored inputData and executes the Flutter task.
+    ///
+    /// - Parameters:
+    ///   - identifier: Task identifier
+    ///   - task: The BGAppRefreshTask instance from iOS
+    ///   - inputData: Input data passed from the Dart side (may be nil)
     @available(iOS 13.0, *)
-    public static func handlePeriodicTask(identifier: String, task: BGAppRefreshTask, earliestBeginInSeconds: Double?) {
+    public static func handlePeriodicTask(identifier: String, task: BGAppRefreshTask, inputData: [String: Any]?) {
         guard let callbackHandle = UserDefaultsHelper.getStoredCallbackHandle(),
               let _ = FlutterCallbackCache.lookupCallbackInformation(callbackHandle)
         else {
             logError("[\(String(describing: self))] \(WMPError.workmanagerNotInitialized.message)")
             return
         }
 
-        // If frequency is not provided it will default to 15 minutes
-        schedulePeriodicTask(taskIdentifier: task.identifier, earliestBeginInSeconds: earliestBeginInSeconds ?? (15 * 60))
+        // Schedule the next occurrence (iOS will determine actual timing based on usage patterns)
+        schedulePeriodicTask(taskIdentifier: task.identifier, earliestBeginInSeconds: 15 * 60)
 
         let operationQueue = OperationQueue()
         let operation = createBackgroundOperation(
             identifier: task.identifier,
-            inputData: nil,
+            inputData: inputData,
             backgroundMode: .backgroundPeriodicTask(identifier: identifier)
         )
 
@@ -57,6 +66,13 @@ public class WorkmanagerPlugin: FlutterPluginAppLifeCycleDelegate, FlutterPlugin
         operationQueue.addOperation(operation)
     }
 
+    /// Starts a one-off background task with the specified input data.
+    ///
+    /// - Parameters:
+    ///   - identifier: Task identifier
+    ///   - taskIdentifier: iOS background task identifier for lifecycle management
+    ///   - inputData: Input data to pass to the Flutter task
+    ///   - delaySeconds: Delay before task execution
     @available(iOS 13.0, *)
     public static func startOneOffTask(identifier: String, taskIdentifier: UIBackgroundTaskIdentifier, inputData: [String: Any]?, delaySeconds: Int64) {
         let operationQueue = OperationQueue()
@@ -70,20 +86,29 @@ public class WorkmanagerPlugin: FlutterPluginAppLifeCycleDelegate, FlutterPlugin
         operationQueue.addOperation(operation)
     }
 
+    /// Registers a periodic background task with iOS BGTaskScheduler.
+    ///
+    /// This method must be called during app initialization (typically in AppDelegate)
+    /// to register the task identifier with iOS. The actual task scheduling with inputData
+    /// happens later when called from the Dart/Flutter side.
+    ///
+    /// - Parameters:
+    ///   - identifier: Unique task identifier that matches the one used in Dart
+    ///   - frequency: Optional frequency hint in seconds (iOS may ignore this based on usage patterns)
+    ///
+    /// - Note: This registers the task handler only. Use Workmanager.registerPeriodicTask()
+    ///   from Dart to actually schedule the task with inputData.
     @objc
     public static func registerPeriodicTask(withIdentifier identifier: String, frequency: NSNumber?) {
         if #available(iOS 13.0, *) {
-            var frequencyInSeconds: Double?
-            if let frequencyValue = frequency {
-                frequencyInSeconds = frequencyValue.doubleValue
-            }
-
             BGTaskScheduler.shared.register(
                 forTaskWithIdentifier: identifier,
                 using: nil
             ) { task in
                 if let task = task as? BGAppRefreshTask {
-                    handlePeriodicTask(identifier: identifier, task: task, earliestBeginInSeconds: frequencyInSeconds)
+                    // Retrieve the stored inputData for this periodic task
+                    let storedInputData = UserDefaultsHelper.getStoredPeriodicTaskInputData(forTaskIdentifier: task.identifier)
+                    handlePeriodicTask(identifier: identifier, task: task, inputData: storedInputData)
                 }
             }
         }
@@ -102,6 +127,12 @@ public class WorkmanagerPlugin: FlutterPluginAppLifeCycleDelegate, FlutterPlugin
         }
     }
 
+    /// Registers a background processing task with iOS BGTaskScheduler.
+    ///
+    /// This method must be called during app initialization (typically in AppDelegate)
+    /// to register the task identifier with iOS for background processing tasks.
+    ///
+    /// - Parameter identifier: Unique task identifier that matches the one used in Dart
     @objc
     public static func registerBGProcessingTask(withIdentifier identifier: String) {
         if #available(iOS 13.0, *) {
@@ -140,6 +171,12 @@ public class WorkmanagerPlugin: FlutterPluginAppLifeCycleDelegate, FlutterPlugin
 
     // MARK: - FlutterPlugin conformance
 
+    /// Sets the plugin registrant callback for background task execution.
+    ///
+    /// This callback is used to register additional plugins when background tasks
+    /// run in a separate Flutter engine instance.
+    ///
+    /// - Parameter callback: The callback to register plugins in the background engine
     @objc
     public static func setPluginRegistrantCallback(_ callback: @escaping FlutterPluginRegistrantCallback) {
         flutterPluginRegistrantCallback = callback
@@ -191,6 +228,13 @@ public class WorkmanagerPlugin: FlutterPluginAppLifeCycleDelegate, FlutterPlugin
 
         executeIfSupportedVoid(completion: completion, feature: "PeriodicTask") {
             let initialDelaySeconds = Double(request.initialDelaySeconds ?? 0)
+
+            // Store the inputData for later retrieval when the task executes
+            UserDefaultsHelper.storePeriodicTaskInputData(
+                request.inputData as? [String: Any],
+                forTaskIdentifier: request.uniqueName
+            )
+
             WorkmanagerPlugin.schedulePeriodicTask(
                 taskIdentifier: request.uniqueName,
                 earliestBeginInSeconds: initialDelaySeconds