Fixed: completeBatchFetching is called on a background thread (#731)

* Fixed breaking issue where completeBatchFetching is called on a background thread when no items are added to the collection

* Changed spaces to tabs for consistency

* Moved return statement for Code Review feedback

* Fixed the same issue in the Objective-C version of ASDKgram

* One more

* Update PhotoFeedModel.m

Fix header

examples/ASDKgram/Sample/PhotoFeedModel.m

@@ -1,20 +1,18 @@
 //
 //  PhotoFeedModel.m
-//  Sample
-//
-//  Created by Hannah Troisi on 2/28/16.
+//  Texture
 //
 //  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
 //  This source code is licensed under the BSD-style license found in the
-//  LICENSE file in the root directory of this source tree. An additional grant
-//  of patent rights can be found in the PATENTS file in the same directory.
+//  LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
+//  grant of patent rights can be found in the PATENTS file in the same directory.
+//
+//  Modifications to this file made after 4/13/2017 are: Copyright (c) 2017-present,
+//  Pinterest, Inc.  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
 //
-//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-//  FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-//  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-//  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//      http://www.apache.org/licenses/LICENSE-2.0
 //
 
 #import "PhotoFeedModel.h"
@@ -184,9 +182,11 @@ - (void)fetchPageWithCompletionBlock:(void (^)(NSArray *))block numResultsToRetu
   // early return if reached end of pages
   if (_totalPages) {
     if (_currentPage == _totalPages) {
-      if (block){
-        block(@[]);
-      }
+      dispatch_async(dispatch_get_main_queue(), ^{
+        if (block) {
+          block(@[]);
+        }
+      });
       return;
     }
   }

examples_extra/ASDKgram-Swift/ASDKgram-Swift/PhotoFeedModel.swift

@@ -67,7 +67,10 @@ final class PhotoFeedModel {
 	private func fetchNextPageOfPopularPhotos(replaceData: Bool, numberOfAdditionsCompletion: @escaping (Int, NetworkingErrors?) -> ()) {
 
 		if currentPage == totalPages, currentPage != 0 {
-			return numberOfAdditionsCompletion(0, .customError("No pages left to parse"))
+			DispatchQueue.main.async {
+				numberOfAdditionsCompletion(0, .customError("No pages left to parse"))
+			}
+            return
 		}
 
 		var newPhotos: [PhotoModel] = []
@@ -106,7 +109,9 @@ final class PhotoFeedModel {
 
 				case .failure(let fail):
 				print(fail)
-				numberOfAdditionsCompletion(0, fail)
+                DispatchQueue.main.async {
+                    numberOfAdditionsCompletion(0, fail)
+                }
 			}
 		}
 	}