[ASViewController] Support optional node (#3021)

* ASViewController can be used without a node
- If a node isn't provided by developers via -initWithNode:, a default one will be created and used internally.
- This allows developers to use ASViewController like a normal UIViewController and as a base class for all view controllers among which some use a node hierarchy and some don't.

* Update ASDKgram to use a shared base ASViewController

* Minor fixes in ASViewController:
- If its node isn't provided by users, don't replace the view controller's view with the default node's view because it might be loaded from a nib.
- Init a vanilla ASDisplayNode if a node isn't provided.

* Some smaller cleanup

* Remove dummy node for ASViewController if it’s used without a node

AsyncDisplayKit/ASViewController.h

@@ -21,25 +21,34 @@ NS_ASSUME_NONNULL_BEGIN
 typedef ASTraitCollection * _Nonnull (^ASDisplayTraitsForTraitCollectionBlock)(UITraitCollection *traitCollection);
 typedef ASTraitCollection * _Nonnull (^ASDisplayTraitsForTraitWindowSizeBlock)(CGSize windowSize);
 
+/**
+ * ASViewController allows you to have a completely node backed hierarchy. It automatically
+ * handles @c ASVisibilityDepth, automatic range mode and propogating @c ASDisplayTraits to contained nodes.
+ *
+ * You can opt-out of node backed hierarchy and use it like a normal UIViewController.
+ * More importantly, you can use it as a base class for all of your view controllers among which some use a node hierarchy and some don't.
+ * See examples/ASDKgram project for actual implementation.
+ */
 @interface ASViewController<__covariant DisplayNodeType : ASDisplayNode *> : UIViewController <ASVisibilityDepth>
 
 /**
- * ASViewController Designated initializer.
- *
- * @discussion ASViewController allows you to have a completely node backed heirarchy. It automatically
- * handles @c ASVisibilityDepth, automatic range mode and propogating @c ASDisplayTraits to contained nodes.
+ * ASViewController initializer.
  *
  * @param node An ASDisplayNode which will provide the root view (self.view)
  * @return An ASViewController instance whose root view will be backed by the provided ASDisplayNode.
  *
  * @see ASVisibilityDepth
  */
-- (instancetype)initWithNode:(DisplayNodeType)node NS_DESIGNATED_INITIALIZER;
+- (instancetype)initWithNode:(DisplayNodeType)node;
+
+NS_ASSUME_NONNULL_END
 
 /**
  * @return node Returns the ASDisplayNode which provides the backing view to the view controller.
  */
-@property (nonatomic, strong, readonly) DisplayNodeType node;
+@property (nonatomic, strong, readonly, null_unspecified) DisplayNodeType node;
+
+NS_ASSUME_NONNULL_BEGIN
 
 /**
  * Set this block to customize the ASDisplayTraits returned when the VC transitions to the given traitCollection.
@@ -91,12 +100,4 @@ typedef ASTraitCollection * _Nonnull (^ASDisplayTraitsForTraitWindowSizeBlock)(C
 
 @end
 
-@interface ASViewController (Unavailable)
-
-- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil AS_UNAVAILABLE("ASViewController requires using -initWithNode:");
-
-- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder AS_UNAVAILABLE("ASViewController requires using -initWithNode:");
-
-@end
-
 NS_ASSUME_NONNULL_END

AsyncDisplayKit/ASViewController.mm

@@ -33,14 +33,24 @@
 
 - (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
 {
-  ASDisplayNodeAssert(NO, @"ASViewController requires using -initWithNode:");
-  return [self initWithNode:[[ASDisplayNode alloc] init]];
+  if (!(self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
+    return nil;
+  }
+  
+  [self _initializeInstance];
+  
+  return self;
 }
 
 - (instancetype)initWithCoder:(NSCoder *)aDecoder
 {
-  ASDisplayNodeAssert(NO, @"ASViewController requires using -initWithNode:");
-  return [self initWithNode:[[ASDisplayNode alloc] init]];
+  if (!(self = [super initWithCoder:aDecoder])) {
+    return nil;
+  }
+  
+  [self _initializeInstance];
+  
+  return self;
 }
 
 - (instancetype)initWithNode:(ASDisplayNode *)node
@@ -49,10 +59,18 @@
     return nil;
   }
   
-  ASDisplayNodeAssertNotNil(node, @"Node must not be nil");
-  ASDisplayNodeAssertTrue(!node.layerBacked);
   _node = node;
+  [self _initializeInstance];
 
+  return self;
+}
+
+- (void)_initializeInstance
+{
+  if (_node == nil) {
+    return;
+  }
+  
   _selfConformsToRangeModeProtocol = [self conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)];
   _nodeConformsToRangeModeProtocol = [_node conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)];
   _automaticallyAdjustRangeModeBasedOnViewEvents = _selfConformsToRangeModeProtocol || _nodeConformsToRangeModeProtocol;
@@ -62,7 +80,7 @@
     // Node already loaded the view
     [self view];
   } else {
-    // If the node didn't load yet add ourselves as on did load observer to laod the view in case the node gets loaded
+    // If the node didn't load yet add ourselves as on did load observer to load the view in case the node gets loaded
     // before the view controller
     __weak __typeof__(self) weakSelf = self;
     [_node onDidLoad:^(__kindof ASDisplayNode * _Nonnull node) {
@@ -71,8 +89,6 @@
       }
     }];
   }
-
-  return self;
 }
 
 - (void)dealloc
@@ -82,13 +98,18 @@
 
 - (void)loadView
 {
-  ASDisplayNodeAssertTrue(!_node.layerBacked);
-  
   // Apple applies a frame and autoresizing masks we need.  Allocating a view is not
   // nearly as expensive as adding and removing it from a hierarchy, and fortunately
   // we can avoid that here.  Enabling layerBacking on a single node in the hierarchy
   // will have a greater performance benefit than the impact of this transient view.
   [super loadView];
+  
+  if (_node == nil) {
+    return;
+  }
+  
+  ASDisplayNodeAssertTrue(!_node.layerBacked);
+  
   UIView *view = self.view;
   CGRect frame = view.frame;
   UIViewAutoresizing autoresizingMask = view.autoresizingMask;
@@ -135,7 +156,7 @@
 {
   if (_ensureDisplayed && self.neverShowPlaceholders) {
     _ensureDisplayed = NO;
-    [self.node recursivelyEnsureDisplaySynchronously:YES];
+    [_node recursivelyEnsureDisplaySynchronously:YES];
   }
   [super viewDidLayoutSubviews];
 }
@@ -212,7 +233,9 @@ ASVisibilityDepthImplementation;
 
 - (void)updateCurrentRangeModeWithModeIfPossible:(ASLayoutRangeMode)rangeMode
 {
-  if (!_automaticallyAdjustRangeModeBasedOnViewEvents) { return; }
+  if (!_automaticallyAdjustRangeModeBasedOnViewEvents) {
+    return;
+  }
   
   if (_selfConformsToRangeModeProtocol) {
     id<ASRangeControllerUpdateRangeProtocol> rangeUpdater = (id<ASRangeControllerUpdateRangeProtocol>)self;
@@ -268,7 +291,7 @@ ASVisibilityDepthImplementation;
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
     // Once we've propagated all the traits, layout this node.
     // Remeasure the node with the latest constrained size – old constrained size may be incorrect.
-    [self.node layoutThatFits:[self nodeConstrainedSize]];
+    [_node layoutThatFits:[self nodeConstrainedSize]];
 #pragma clang diagnostic pop
   }
 }
@@ -286,7 +309,7 @@ ASVisibilityDepthImplementation;
 {
   [super didRotateFromInterfaceOrientation:fromInterfaceOrientation];
   
-  ASPrimitiveTraitCollection traitCollection = self.node.primitiveTraitCollection;
+  ASPrimitiveTraitCollection traitCollection = _node.primitiveTraitCollection;
   traitCollection.containerSize = self.view.bounds.size;
   [self propagateNewTraitCollection:traitCollection];
 }

examples/ASDKgram/Sample.xcodeproj/project.pbxproj

@@ -36,12 +36,14 @@
 		CC5532171E15CC1E0011C01F /* ASCollectionSectionController.m in Sources */ = {isa = PBXBuildFile; fileRef = CC5532161E15CC1E0011C01F /* ASCollectionSectionController.m */; };
 		CC6350BB1E1C482D002BC613 /* TailLoadingNode.m in Sources */ = {isa = PBXBuildFile; fileRef = CC6350BA1E1C482D002BC613 /* TailLoadingNode.m */; };
 		CC85250F1E36B392008EABE6 /* FeedHeaderNode.m in Sources */ = {isa = PBXBuildFile; fileRef = CC85250E1E36B392008EABE6 /* FeedHeaderNode.m */; };
+		E5F128F01E09625400B4335F /* PhotoFeedBaseController.m in Sources */ = {isa = PBXBuildFile; fileRef = E5F128EF1E09625400B4335F /* PhotoFeedBaseController.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
 		0585427F19D4DBE100606EA6 /* Default-568h@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; name = "Default-568h@2x.png"; path = "../Default-568h@2x.png"; sourceTree = "<group>"; };
 		05E2128119D4DB510098F589 /* Sample.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Sample.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		3D24B17D1E4A4E7A9566C5E9 /* libPods.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = libPods.a; sourceTree = BUILT_PRODUCTS_DIR; };
+		69CE83D91E515036004AA230 /* PhotoFeedControllerProtocol.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PhotoFeedControllerProtocol.h; sourceTree = "<group>"; };
 		6C2C82AA19EE274300767484 /* Default-667h@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "Default-667h@2x.png"; sourceTree = SOURCE_ROOT; };
 		6C2C82AB19EE274300767484 /* Default-736h@3x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "Default-736h@3x.png"; sourceTree = SOURCE_ROOT; };
 		76229A761CBB79E000B62CEF /* WindowWithStatusBarUnderlay.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WindowWithStatusBarUnderlay.h; sourceTree = "<group>"; };
@@ -97,6 +99,8 @@
 		CC85250D1E36B392008EABE6 /* FeedHeaderNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FeedHeaderNode.h; sourceTree = "<group>"; };
 		CC85250E1E36B392008EABE6 /* FeedHeaderNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FeedHeaderNode.m; sourceTree = "<group>"; };
 		D09B5DF0BFB37583DE8F3142 /* Pods-Sample.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Sample.release.xcconfig"; path = "Pods/Target Support Files/Pods-Sample/Pods-Sample.release.xcconfig"; sourceTree = "<group>"; };
+		E5F128EE1E09612700B4335F /* PhotoFeedBaseController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PhotoFeedBaseController.h; sourceTree = "<group>"; };
+		E5F128EF1E09625400B4335F /* PhotoFeedBaseController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PhotoFeedBaseController.m; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -183,6 +187,9 @@
 		767A5F141CAA3D8A004CDA8D /* Controller */ = {
 			isa = PBXGroup;
 			children = (
+				69CE83D91E515036004AA230 /* PhotoFeedControllerProtocol.h */,
+				E5F128EE1E09612700B4335F /* PhotoFeedBaseController.h */,
+				E5F128EF1E09625400B4335F /* PhotoFeedBaseController.m */,
 				767A5F161CAA3D96004CDA8D /* UIKit */,
 				767A5F151CAA3D90004CDA8D /* ASDK */,
 				CC00D1581E159132004E5502 /* ASDK-ListKit */,
@@ -380,7 +387,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "diff \"${PODS_ROOT}/../Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [ $? != 0 ] ; then\n    # print error to STDERR\n    echo \"error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\" >&2\n    exit 1\nfi\n";
+			shellScript = "diff \"${PODS_ROOT}/../Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [[ $? != 0 ]] ; then\n    cat << EOM\nerror: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\nEOM\n    exit 1\nfi\n";
 			showEnvVarsInLog = 0;
 		};
 		F012A6F39E0149F18F564F50 /* [CP] Copy Pods Resources */ = {
@@ -412,6 +419,7 @@
 				768843821CAA37EF00D8629E /* CommentModel.m in Sources */,
 				768843831CAA37EF00D8629E /* CommentsNode.m in Sources */,
 				768843961CAA37EF00D8629E /* Utilities.m in Sources */,
+				E5F128F01E09625400B4335F /* PhotoFeedBaseController.m in Sources */,
 				768843931CAA37EF00D8629E /* UserModel.m in Sources */,
 				CC5532171E15CC1E0011C01F /* ASCollectionSectionController.m in Sources */,
 				768843801CAA37EF00D8629E /* AppDelegate.m in Sources */,

examples/ASDKgram/Sample/AppDelegate.h

@@ -17,10 +17,6 @@
 //  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-@protocol PhotoFeedControllerProtocol <NSObject>
-- (void)resetAllData;
-@end
-
 @interface AppDelegate : UIResponder <UIApplicationDelegate>
 
 @end

examples/ASDKgram/Sample/PhotoFeedBaseController.h

@@ -0,0 +1,39 @@
+//
+//  PhotoFeedBaseController.h
+//  Sample
+//
+//  Created by Huy Nguyen on 20/12/16.
+//
+//  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.
+//
+//  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.
+//
+
+#import <AsyncDisplayKit/AsyncDisplayKit.h>
+#import "PhotoFeedControllerProtocol.h"
+
+@protocol PhotoFeedControllerProtocol;
+@class PhotoFeedModel;
+
+@interface PhotoFeedBaseController : ASViewController <PhotoFeedControllerProtocol>
+
+@property (nonatomic, strong, readonly) PhotoFeedModel *photoFeed;
+@property (nonatomic, strong, readonly) UITableView *tableView;
+
+- (void)refreshFeed;
+- (void)insertNewRows:(NSArray *)newPhotos;
+
+#pragma mark - Subclasses must override these methods
+
+- (void)loadPage;
+- (void)requestCommentsForPhotos:(NSArray *)newPhotos;
+
+@end

examples/ASDKgram/Sample/PhotoFeedBaseController.m

@@ -0,0 +1,123 @@
+//
+//  PhotoFeedBaseController.m
+//  Sample
+//
+//  Created by Huy Nguyen on 20/12/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+//  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.
+//
+//  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.
+//
+
+#import "PhotoFeedBaseController.h"
+#import "PhotoFeedModel.h"
+
+@implementation PhotoFeedBaseController
+{
+  UIActivityIndicatorView *_activityIndicatorView;
+}
+
+// -loadView is guaranteed to be called on the main thread and is the appropriate place to
+// set up an UIKit objects you may be using.
+- (void)loadView
+{
+  [super loadView];
+  
+  _activityIndicatorView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
+  
+  _photoFeed = [[PhotoFeedModel alloc] initWithPhotoFeedModelType:PhotoFeedModelTypePopular imageSize:[self imageSizeForScreenWidth]];
+  [self refreshFeed];
+  
+  CGSize boundSize = self.view.bounds.size;
+  [_activityIndicatorView sizeToFit];
+  CGRect refreshRect = _activityIndicatorView.frame;
+  refreshRect.origin = CGPointMake((boundSize.width - _activityIndicatorView.frame.size.width) / 2.0,
+                                   (boundSize.height - _activityIndicatorView.frame.size.height) / 2.0);
+  _activityIndicatorView.frame = refreshRect;
+  [self.view addSubview:_activityIndicatorView];
+  
+  self.tableView.allowsSelection = NO;
+  self.tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
+  
+  self.view.backgroundColor = [UIColor whiteColor];
+}
+
+- (void)refreshFeed
+{
+  [_activityIndicatorView startAnimating];
+  // small first batch
+  [_photoFeed refreshFeedWithCompletionBlock:^(NSArray *newPhotos){
+    
+    [_activityIndicatorView stopAnimating];
+    
+    [self insertNewRows:newPhotos];
+    [self requestCommentsForPhotos:newPhotos];
+    
+    // immediately start second larger fetch
+    [self loadPage];
+    
+  } numResultsToReturn:4];
+}
+
+- (void)insertNewRows:(NSArray *)newPhotos
+{
+  NSInteger section = 0;
+  NSMutableArray *indexPaths = [NSMutableArray array];
+  
+  NSInteger newTotalNumberOfPhotos = [_photoFeed numberOfItemsInFeed];
+  for (NSInteger row = newTotalNumberOfPhotos - newPhotos.count; row < newTotalNumberOfPhotos; row++) {
+    NSIndexPath *path = [NSIndexPath indexPathForRow:row inSection:section];
+    [indexPaths addObject:path];
+  }
+  [self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationNone];
+}
+
+- (UIStatusBarStyle)preferredStatusBarStyle
+{
+  return UIStatusBarStyleLightContent;
+}
+
+- (CGSize)imageSizeForScreenWidth
+{
+  CGRect screenRect   = [[UIScreen mainScreen] bounds];
+  CGFloat screenScale = [[UIScreen mainScreen] scale];
+  return CGSizeMake(screenRect.size.width * screenScale, screenRect.size.width * screenScale);
+}
+
+#pragma mark - PhotoFeedViewControllerProtocol
+
+- (void)resetAllData
+{
+  [_photoFeed clearFeed];
+  [self.tableView reloadData];
+  [self refreshFeed];
+}
+
+#pragma mark - Subclassing
+
+- (UITableView *)tableView
+{
+  NSAssert(NO, @"Subclasses must override this method");
+  return nil;
+}
+
+- (void)loadPage
+{
+  NSAssert(NO, @"Subclasses must override this method");
+}
+
+- (void)requestCommentsForPhotos:(NSArray *)newPhotos
+{
+  NSAssert(NO, @"Subclasses must override this method");
+}
+
+@end

examples/ASDKgram/Sample/PhotoFeedControllerProtocol.h

@@ -0,0 +1,13 @@
+//
+//  PhotoFeedControllerProtocol.h
+//  Sample
+//
+//  Created by Michael Schneider on 2/12/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@protocol PhotoFeedControllerProtocol <NSObject>
+- (void)resetAllData;
+@end

examples/ASDKgram/Sample/PhotoFeedListKitViewController.h

@@ -7,7 +7,7 @@
 //
 
 #import <AsyncDisplayKit/AsyncDisplayKit.h>
-#import "AppDelegate.h"
+#import "PhotoFeedControllerProtocol.h"
 
 @interface PhotoFeedListKitViewController<ASCollectionNode> : ASViewController <PhotoFeedControllerProtocol>
 

examples/ASDKgram/Sample/PhotoFeedNodeController.h

@@ -17,9 +17,8 @@
 //  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-#import <AsyncDisplayKit/AsyncDisplayKit.h>
-#import "AppDelegate.h"
+#import "PhotoFeedBaseController.h"
 
-@interface PhotoFeedNodeController : ASViewController <PhotoFeedControllerProtocol>
+@interface PhotoFeedNodeController : PhotoFeedBaseController
 
 @end

examples/ASDKgram/Sample/PhotoFeedNodeController.m

@@ -31,9 +31,7 @@
 
 @implementation PhotoFeedNodeController
 {
-  PhotoFeedModel          *_photoFeed;
-  ASTableNode             *_tableNode;
-  UIActivityIndicatorView *_activityIndicatorView;
+  ASTableNode *_tableNode;
 }
 
 #pragma mark - Lifecycle
@@ -51,7 +49,6 @@
     
     _tableNode.dataSource = self;
     _tableNode.delegate = self;
-    
   }
   
   return self;
@@ -63,112 +60,48 @@
 {
   [super loadView];
   
-  _activityIndicatorView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
-  
-  _photoFeed = [[PhotoFeedModel alloc] initWithPhotoFeedModelType:PhotoFeedModelTypePopular imageSize:[self imageSizeForScreenWidth]];
-  [self refreshFeed];
-  
-  CGSize boundSize = self.view.bounds.size;
-
-  [_activityIndicatorView sizeToFit];
-  CGRect refreshRect = _activityIndicatorView.frame;
-  refreshRect.origin = CGPointMake((boundSize.width - _activityIndicatorView.frame.size.width) / 2.0,
-                                   (boundSize.height - _activityIndicatorView.frame.size.height) / 2.0);
-  _activityIndicatorView.frame = refreshRect;
-  
-  [self.view addSubview:_activityIndicatorView];
-  
-  self.view.backgroundColor = [UIColor whiteColor];
-  _tableNode.view.allowsSelection = NO;
-  _tableNode.view.separatorStyle = UITableViewCellSeparatorStyleNone;
   _tableNode.view.leadingScreensForBatching = AUTO_TAIL_LOADING_NUM_SCREENFULS;  // overriding default of 2.0
 }
 
-#pragma mark - helper methods
-
-- (void)refreshFeed
-{
-  [_activityIndicatorView startAnimating];
-  // small first batch
-  [_photoFeed refreshFeedWithCompletionBlock:^(NSArray *newPhotos){
-    
-    [_activityIndicatorView stopAnimating];
-    
-    [self insertNewRowsInTableNode:newPhotos];
-//    [self requestCommentsForPhotos:newPhotos];
-    
-    // immediately start second larger fetch
-    [self loadPageWithContext:nil];
-    
-  } numResultsToReturn:4];
-}
-
 - (void)loadPageWithContext:(ASBatchContext *)context
 {
-  [_photoFeed requestPageWithCompletionBlock:^(NSArray *newPhotos){
+  [self.photoFeed requestPageWithCompletionBlock:^(NSArray *newPhotos){
     
-    [self insertNewRowsInTableNode:newPhotos];
-//    [self requestCommentsForPhotos:newPhotos];
+    [self insertNewRows:newPhotos];
+    [self requestCommentsForPhotos:newPhotos];
     if (context) {
       [context completeBatchFetching:YES];
     }
   } numResultsToReturn:20];
 }
 
-//- (void)requestCommentsForPhotos:(NSArray *)newPhotos
-//{
-//  for (PhotoModel *photo in newPhotos) {
-//    [photo.commentFeed refreshFeedWithCompletionBlock:^(NSArray *newComments) {
-//      
-//      NSInteger rowNum      = [_photoFeed indexOfPhotoModel:photo];
-//      NSIndexPath *cellPath = [NSIndexPath indexPathForRow:rowNum inSection:0];
-//      PhotoCellNode *cell   = (PhotoCellNode *)[_tableNode.view nodeForRowAtIndexPath:cellPath];
-//      
-//      if (cell) {
-//        [cell loadCommentsForPhoto:photo];
-//        [_tableNode.view beginUpdates];
-//        [_tableNode.view endUpdates];
-//      }
-//    }];
-//  }
-//}
+#pragma mark - Subclassing
 
-- (void)insertNewRowsInTableNode:(NSArray *)newPhotos
+- (UITableView *)tableView
 {
-  NSInteger section = 0;
-  NSMutableArray *indexPaths = [NSMutableArray array];
-  
-  NSUInteger newTotalNumberOfPhotos = [_photoFeed numberOfItemsInFeed];
-  for (NSUInteger row = newTotalNumberOfPhotos - newPhotos.count; row < newTotalNumberOfPhotos; row++) {
-    NSIndexPath *path = [NSIndexPath indexPathForRow:row inSection:section];
-    [indexPaths addObject:path];
-  }
-  
-  [_tableNode insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationNone];
+  return _tableNode.view;
 }
 
-- (UIStatusBarStyle)preferredStatusBarStyle
+- (void)loadPage
 {
-  return UIStatusBarStyleLightContent;
+  [self loadPageWithContext:nil];
 }
 
-- (CGSize)imageSizeForScreenWidth
+- (void)requestCommentsForPhotos:(NSArray *)newPhotos
 {
-  CGRect screenRect   = [[UIScreen mainScreen] bounds];
-  CGFloat screenScale = [[UIScreen mainScreen] scale];
-  return CGSizeMake(screenRect.size.width * screenScale, screenRect.size.width * screenScale);
+  // Do nothing (#1530).
 }
 
 #pragma mark - ASTableDataSource methods
 
 - (NSInteger)tableNode:(ASTableNode *)tableNode numberOfRowsInSection:(NSInteger)section
 {
-  return [_photoFeed numberOfItemsInFeed];
+  return [self.photoFeed numberOfItemsInFeed];
 }
 
 - (ASCellNodeBlock)tableNode:(ASTableNode *)tableNode nodeBlockForRowAtIndexPath:(NSIndexPath *)indexPath
 {
-  PhotoModel *photoModel = [_photoFeed objectAtIndex:indexPath.row];
+  PhotoModel *photoModel = [self.photoFeed objectAtIndex:indexPath.row];
   // this will be executed on a background thread - important to make sure it's thread safe
   ASCellNode *(^ASCellNodeBlock)() = ^ASCellNode *() {
     PhotoCellNode *cellNode = [[PhotoCellNode alloc] initWithPhotoObject:photoModel];
@@ -187,13 +120,4 @@
   [self loadPageWithContext:context];
 }
 
-#pragma mark - PhotoFeedViewControllerProtocol
-
-- (void)resetAllData
-{
-  [_photoFeed clearFeed];
-  [_tableNode reloadData];
-  [self refreshFeed];
-}
-
 @end

examples/ASDKgram/Sample/PhotoFeedViewController.h

@@ -17,8 +17,8 @@
 //  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-#import "AppDelegate.h"
+#import "PhotoFeedBaseController.h"
 
-@interface PhotoFeedViewController : UIViewController <PhotoFeedControllerProtocol>
+@interface PhotoFeedViewController : PhotoFeedBaseController
 
 @end

examples/ASDKgram/Sample/PhotoFeedViewController.m

@@ -30,9 +30,7 @@
 
 @implementation PhotoFeedViewController
 {
-  PhotoFeedModel          *_photoFeed;
-  UITableView             *_tableView;
-  UIActivityIndicatorView *_activityIndicatorView;
+  UITableView *_tableView;
 }
 
 #pragma mark - Lifecycle
@@ -49,8 +47,6 @@
     _tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth;
     _tableView.delegate = self;
     _tableView.dataSource = self;
-    
-    _activityIndicatorView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
   }
   
   return self;
@@ -61,51 +57,22 @@
 {
   [super viewDidLoad];
   
-  _photoFeed = [[PhotoFeedModel alloc] initWithPhotoFeedModelType:PhotoFeedModelTypePopular imageSize:[self imageSizeForScreenWidth]];
-  [self refreshFeed];
-  
-  CGSize boundSize = self.view.bounds.size;
-  
   [self.view addSubview:_tableView];
-  
   _tableView.frame = self.view.bounds;
-  _tableView.allowsSelection = NO;
-  _tableView.separatorStyle  = UITableViewCellSeparatorStyleNone;
   [_tableView registerClass:[PhotoTableViewCell class] forCellReuseIdentifier:@"photoCell"];
-  
-  [self.view addSubview:_activityIndicatorView];
-  
-  [_activityIndicatorView sizeToFit];
-  CGRect refreshRect = _activityIndicatorView.frame;
-  refreshRect.origin = CGPointMake((boundSize.width - _activityIndicatorView.frame.size.width) / 2.0,
-                                   (boundSize.height - _activityIndicatorView.frame.size.height) / 2.0);
-  _activityIndicatorView.frame = refreshRect;
 }
 
-#pragma mark - helper methods
+#pragma mark - Subclassing
 
-- (void)refreshFeed
+- (UITableView *)tableView
 {
-  [_activityIndicatorView startAnimating];
-  
-  // small first batch
-  [_photoFeed refreshFeedWithCompletionBlock:^(NSArray *newPhotos){
-    
-    [_activityIndicatorView stopAnimating];
-    
-    [self insertNewRowsInTableView:newPhotos];
-    [self requestCommentsForPhotos:newPhotos];
-    
-    // immediately start second larger fetch
-    [self loadPage];
-    
-  } numResultsToReturn:4];
+  return _tableView;
 }
 
 - (void)loadPage
 {
-  [_photoFeed requestPageWithCompletionBlock:^(NSArray *newPhotos){
-    [self insertNewRowsInTableView:newPhotos];
+  [self.photoFeed requestPageWithCompletionBlock:^(NSArray *newPhotos){
+    [self insertNewRows:newPhotos];
     [self requestCommentsForPhotos:newPhotos];
   } numResultsToReturn:20];
 }
@@ -115,7 +82,7 @@
   for (PhotoModel *photo in newPhotos) {
     [photo.commentFeed refreshFeedWithCompletionBlock:^(NSArray *newComments) {
       
-      NSInteger rowNum         = [_photoFeed indexOfPhotoModel:photo];
+      NSInteger rowNum         = [self.photoFeed indexOfPhotoModel:photo];
       NSIndexPath *cellPath    = [NSIndexPath indexPathForRow:rowNum inSection:0];
       PhotoTableViewCell *cell = [_tableView cellForRowAtIndexPath:cellPath];
       
@@ -135,49 +102,24 @@
   }
 }
 
-- (void)insertNewRowsInTableView:(NSArray *)newPhotos
-{
-  NSInteger section = 0;
-  NSMutableArray *indexPaths = [NSMutableArray array];
-  
-  NSInteger newTotalNumberOfPhotos = [_photoFeed numberOfItemsInFeed];
-  for (NSInteger row = newTotalNumberOfPhotos - newPhotos.count; row < newTotalNumberOfPhotos; row++) {
-    NSIndexPath *path = [NSIndexPath indexPathForRow:row inSection:section];
-    [indexPaths addObject:path];
-  }
-  [_tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationNone];
-}
-
-- (UIStatusBarStyle)preferredStatusBarStyle
-{
-  return UIStatusBarStyleLightContent;
-}
-
-- (CGSize)imageSizeForScreenWidth
-{
-  CGRect screenRect   = [[UIScreen mainScreen] bounds];
-  CGFloat screenScale = [[UIScreen mainScreen] scale];
-  return CGSizeMake(screenRect.size.width * screenScale, screenRect.size.width * screenScale);
-}
-
 #pragma mark - UITableViewDataSource methods
 
 - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
 {
-  return [_photoFeed numberOfItemsInFeed];
+  return [self.photoFeed numberOfItemsInFeed];
 }
 
 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
 {
   PhotoTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"photoCell" forIndexPath:indexPath];
-  [cell updateCellWithPhotoObject:[_photoFeed objectAtIndex:indexPath.row]];
+  [cell updateCellWithPhotoObject:[self.photoFeed objectAtIndex:indexPath.row]];
   
   return cell;
 }
 
 - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(nonnull NSIndexPath *)indexPath
 {
-  PhotoModel *photo = [_photoFeed objectAtIndex:indexPath.row];
+  PhotoModel *photo = [self.photoFeed objectAtIndex:indexPath.row];
   return [PhotoTableViewCell heightForPhotoModel:photo withWidth:self.view.bounds.size.width];
 }
 
@@ -196,13 +138,4 @@
   }
 }
 
-#pragma mark - PhotoFeedViewControllerProtocol
-
-- (void)resetAllData
-{
-  [_photoFeed clearFeed];
-  [_tableView reloadData];
-  [self refreshFeed];
-}
-
 @end