[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 @@ @implementation ASViewController
 
 - (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 @@ - (instancetype)initWithNode:(ASDisplayNode *)node
     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 @@ - (instancetype)initWithNode:(ASDisplayNode *)node
     // 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 @@ - (instancetype)initWithNode:(ASDisplayNode *)node
       }
     }];
   }
-
-  return self;
 }
 
 - (void)dealloc
@@ -82,13 +98,18 @@ - (void)dealloc
 
 - (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 @@ - (void)viewDidLayoutSubviews
 {
   if (_ensureDisplayed && self.neverShowPlaceholders) {
     _ensureDisplayed = NO;
-    [self.node recursivelyEnsureDisplaySynchronously:YES];
+    [_node recursivelyEnsureDisplaySynchronously:YES];
   }
   [super viewDidLayoutSubviews];
 }
@@ -212,7 +233,9 @@ - (void)setAutomaticallyAdjustRangeModeBasedOnViewEvents:(BOOL)automaticallyAdju
 
 - (void)updateCurrentRangeModeWithModeIfPossible:(ASLayoutRangeMode)rangeMode
 {
-  if (!_automaticallyAdjustRangeModeBasedOnViewEvents) { return; }
+  if (!_automaticallyAdjustRangeModeBasedOnViewEvents) {
+    return;
+  }
 
   if (_selfConformsToRangeModeProtocol) {
     id<ASRangeControllerUpdateRangeProtocol> rangeUpdater = (id<ASRangeControllerUpdateRangeProtocol>)self;
@@ -268,7 +291,7 @@ - (void)propagateNewTraitCollection:(ASPrimitiveTraitCollection)traitCollection
 #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 @@ - (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceO
 {
   [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