Remote notification completion handler

Summary:
**Motivation**
To allow handling of remote notifications using the preferred delegate [application:didReceiveRemoteNotification:fetchCompletionHandler](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIApplicationDelegate_Protocol/#//apple_ref/occ/intfm/UIApplicationDelegate/application:didReceiveRemoteNotification:fetchCompletionHandler:).

React native right now is setup to use [application:didReceiveRemoteNotification](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIApplicationDelegate_Protocol/#//apple_ref/occ/intfm/UIApplicationDelegate/application:didReceiveRemoteNotification:) which doesn't give the engineer the option to call back to the app via a completion handler and inform the app that it is done with handling the push notification.

The primary reason to use the `fetchCompletionHandler` would be to wake up the app to fetch updates so the next time the user opens the app it will be up to date.

A new method will be exposed: `PushNotificationIOS#
Closes https://github.com/facebook/react-native/pull/8040

Differential Revision: D4081766

Pulled By: bestander

fbshipit-source-id: 2819061bd3a926cb1c9c743af5aabab8c0faec3d

Libraries/PushNotificationIOS/PushNotificationIOS.js

@@ -24,6 +24,12 @@ const NOTIF_REGISTER_EVENT = 'remoteNotificationsRegistered';
 const NOTIF_REGISTRATION_ERROR_EVENT = 'remoteNotificationRegistrationError';
 const DEVICE_LOCAL_NOTIF_EVENT = 'localNotificationReceived';
 
+export type FetchResult = {
+  NewData: string,
+  NoData: string,
+  ResultFailed: string,
+};
+
 /**
  * An event emitted by PushNotificationIOS.
  */
@@ -84,6 +90,17 @@ export type PushNotificationEventName = $Enum<{
  *    {
  *     [RCTPushNotificationManager didRegisterForRemoteNotificationsWithDeviceToken:deviceToken];
  *    }
+ *    // Required for the notification event. You must call the completion handler after handling the remote notification.
+ *    - (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
+ *                                                           fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
+ *    {
+ *       [RCTPushNotificationManager didReceiveRemoteNotification:userInfo fetchCompletionHandler:completionHandler];
+ *    }
+ *    // Optionally implement this method over the previous to receive remote notifications. However
+ *    // implement the application:didReceiveRemoteNotification:fetchCompletionHandler: method instead of this one whenever possible.
+ *    // If your delegate implements both methods, the app object calls the `application:didReceiveRemoteNotification:fetchCompletionHandler:` method
+ *    // Either this method or `application:didReceiveRemoteNotification:fetchCompletionHandler:` is required in order to receive remote notifications.
+ *    //
  *    // Required for the registrationError event.
  *    - (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error
  *    {
@@ -106,6 +123,15 @@ class PushNotificationIOS {
   _alert: string | Object;
   _sound: string;
   _badgeCount: number;
+  _notificationId: string;
+  _isRemote: boolean;
+  _remoteNotificationCompleteCalllbackCalled: boolean;
+
+  static FetchResult: FetchResult = {
+    NewData: 'UIBackgroundFetchResultNewData',
+    NoData: 'UIBackgroundFetchResultNoData',
+    ResultFailed: 'UIBackgroundFetchResultFailed',
+  };
 
   /**
    * Schedules the localNotification for immediate presentation.
@@ -341,6 +367,11 @@ class PushNotificationIOS {
    */
   constructor(nativeNotif: Object) {
     this._data = {};
+    this._remoteNotificationCompleteCalllbackCalled = false;
+    this._isRemote = nativeNotif.remote;
+    if (this._isRemote) {
+      this._notificationId = nativeNotif.notificationId;
+    }
 
     if (nativeNotif.remote) {
       // Extract data from Apple's `aps` dict as defined:
@@ -364,6 +395,28 @@ class PushNotificationIOS {
     }
   }
 
+  /**
+   * This method is available for remote notifications that have been received via:
+   * `application:didReceiveRemoteNotification:fetchCompletionHandler:`
+   * https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIApplicationDelegate_Protocol/#//apple_ref/occ/intfm/UIApplicationDelegate/application:didReceiveRemoteNotification:fetchCompletionHandler:
+   *
+   * Call this to execute when the remote notification handling is complete. When
+   * calling this block, pass in the fetch result value that best describes
+   * the results of your operation. You *must* call this handler and should do so
+   * as soon as possible. For a list of possible values, see `PushNotificationIOS.FetchResult`.
+   *
+   * If you do not call this method your background remote notifications could
+   * be throttled, to read more about it see the above documentation link.
+   */
+  finish(fetchResult: FetchResult) {
+    if (!this._isRemote || !this._notificationId || this._remoteNotificationCompleteCalllbackCalled) {
+      return;
+    }
+    this._remoteNotificationCompleteCalllbackCalled = true;
+
+    RCTPushNotificationManager.onFinishRemoteNotification(this._notificationId, fetchResult);
+  }
+
   /**
    * An alias for `getAlert` to get the notification's main message string
    */

Libraries/PushNotificationIOS/RCTPushNotificationManager.h

@@ -11,10 +11,13 @@
 
 @interface RCTPushNotificationManager : RCTEventEmitter
 
+typedef void (^RCTRemoteNotificationCallback)(UIBackgroundFetchResult result);
+
 #if !TARGET_OS_TV
 + (void)didRegisterUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings;
 + (void)didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken;
 + (void)didReceiveRemoteNotification:(NSDictionary *)notification;
++ (void)didReceiveRemoteNotification:(NSDictionary *)notification fetchCompletionHandler:(RCTRemoteNotificationCallback)completionHandler;
 + (void)didReceiveLocalNotification:(UILocalNotification *)notification;
 + (void)didFailToRegisterForRemoteNotificationsWithError:(NSError *)error;
 #endif

Libraries/PushNotificationIOS/RCTPushNotificationManager.m

@@ -39,6 +39,10 @@ RCT_ENUM_CONVERTER(NSCalendarUnit,
 
 @end
 
+@interface RCTPushNotificationManager ()
+@property (nonatomic, strong) NSMutableDictionary *remoteNotificationCallbacks;
+@end
+
 @implementation RCTConvert (UILocalNotification)
 
 + (UILocalNotification *)UILocalNotification:(id)json
@@ -58,6 +62,12 @@ RCT_ENUM_CONVERTER(NSCalendarUnit,
   return notification;
 }
 
+RCT_ENUM_CONVERTER(UIBackgroundFetchResult, (@{
+  @"UIBackgroundFetchResultNewData": @(UIBackgroundFetchResultNewData),
+  @"UIBackgroundFetchResultNoData": @(UIBackgroundFetchResultNoData),
+  @"UIBackgroundFetchResultFailed": @(UIBackgroundFetchResultFailed),
+}), UIBackgroundFetchResultNoData, integerValue)
+
 @end
 #endif //TARGET_OS_TV
 
@@ -167,9 +177,19 @@ RCT_EXPORT_MODULE()
 
 + (void)didReceiveRemoteNotification:(NSDictionary *)notification
 {
+  NSDictionary *userInfo = @{@"notification": notification};
   [[NSNotificationCenter defaultCenter] postNotificationName:RCTRemoteNotificationReceived
                                                       object:self
-                                                    userInfo:notification];
+                                                    userInfo:userInfo];
+}
+
++ (void)didReceiveRemoteNotification:(NSDictionary *)notification
+              fetchCompletionHandler:(RCTRemoteNotificationCallback)completionHandler
+{
+  NSDictionary *userInfo = @{@"notification": notification, @"completionHandler": completionHandler};
+  [[NSNotificationCenter defaultCenter] postNotificationName:RCTRemoteNotificationReceived
+                                                      object:self
+                                                    userInfo:userInfo];
 }
 
 + (void)didReceiveLocalNotification:(UILocalNotification *)notification
@@ -186,9 +206,20 @@ RCT_EXPORT_MODULE()
 
 - (void)handleRemoteNotificationReceived:(NSNotification *)notification
 {
-  NSMutableDictionary *userInfo = [notification.userInfo mutableCopy];
-  userInfo[@"remote"] = @YES;
-  [self sendEventWithName:@"remoteNotificationReceived" body:userInfo];
+  NSMutableDictionary *remoteNotification = [NSMutableDictionary dictionaryWithDictionary:notification.userInfo[@"notification"]];
+  RCTRemoteNotificationCallback completionHandler = notification.userInfo[@"completionHandler"];
+  NSString* notificationId = [[NSUUID UUID] UUIDString];
+  remoteNotification[@"notificationId"] = notificationId;
+  remoteNotification[@"remote"] = @YES;
+  if (completionHandler) {
+    if (!self.remoteNotificationCallbacks) {
+      // Lazy initialization
+      self.remoteNotificationCallbacks = [NSMutableDictionary dictionary];
+    }
+    self.remoteNotificationCallbacks[notificationId] = completionHandler;
+  }
+
+  [self sendEventWithName:@"remoteNotificationReceived" body:notification.userInfo];
 }
 
 - (void)handleRemoteNotificationsRegistered:(NSNotification *)notification
@@ -224,6 +255,16 @@ RCT_EXPORT_MODULE()
   _requestPermissionsResolveBlock = nil;
 }
 
+RCT_EXPORT_METHOD(onFinishRemoteNotification:(NSString*)notificationId fetchResult:(UIBackgroundFetchResult)result) {
+  RCTRemoteNotificationCallback completionHandler = self.remoteNotificationCallbacks[notificationId];
+  if (!completionHandler) {
+    RCTLogError(@"There is no completion handler with notification id: %@", notificationId)
+    return;
+  }
+  completionHandler(result);
+  [self.remoteNotificationCallbacks removeObjectForKey:notificationId];
+}
+
 /**
  * Update the application icon badge number on the home screen
  */