Swiftgram/AsyncDisplayKit/ASViewController.mm

//
//  ASViewController.m
//  AsyncDisplayKit
//
//  Created by Huy Nguyen on 16/09/15.
//  Copyright (c) 2015 Facebook. All rights reserved.
//

#import "ASViewController.h"
#import "ASAssert.h"
#import "ASDimension.h"
#import "ASDisplayNode+FrameworkPrivate.h"
#import "ASDisplayNode+Beta.h"
#import "ASRangeControllerUpdateRangeProtocol+Beta.h"

#define AS_LOG_VISIBILITY_CHANGES 0

@implementation ASViewController
{
  BOOL _ensureDisplayed;
  BOOL _automaticallyAdjustRangeModeBasedOnViewEvents;
  BOOL _parentManagesVisibilityDepth;
  NSInteger _visibilityDepth;
}

- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
  ASDisplayNodeAssert(NO, @"ASViewController requires using -initWithNode:");
  return [self initWithNode:[[ASDisplayNode alloc] init]];
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
  ASDisplayNodeAssert(NO, @"ASViewController requires using -initWithNode:");
  return [self initWithNode:[[ASDisplayNode alloc] init]];
}

- (instancetype)initWithNode:(ASDisplayNode *)node
{
  if (!(self = [super initWithNibName:nil bundle:nil])) {
    return nil;
  }
  
  ASDisplayNodeAssertNotNil(node, @"Node must not be nil");
  ASDisplayNodeAssertTrue(!node.layerBacked);
  _node = node;

  _automaticallyAdjustRangeModeBasedOnViewEvents = NO;
  
  return self;
}

- (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];
  UIView *view = self.view;
  CGRect frame = view.frame;
  UIViewAutoresizing autoresizingMask = view.autoresizingMask;
  
  // We have what we need, so now create and assign the view we actually want.
  view = _node.view;
  _node.frame = frame;
  _node.autoresizingMask = autoresizingMask;
  self.view = view;
}

- (void)viewWillLayoutSubviews
{
  [super viewWillLayoutSubviews];
  [_node measureWithSizeRange:[self nodeConstrainedSize]];
}

- (void)viewDidLayoutSubviews
{
  if (_ensureDisplayed && self.neverShowPlaceholders) {
    _ensureDisplayed = NO;
    [self.node recursivelyEnsureDisplaySynchronously:YES];
  }
  [super viewDidLayoutSubviews];
}

ASVisibilityDidMoveToParentViewController;

- (void)viewWillAppear:(BOOL)animated
{
  [super viewWillAppear:animated];
  _ensureDisplayed = YES;
  [_node measureWithSizeRange:[self nodeConstrainedSize]];
  [_node recursivelyFetchData];
  
  if (_parentManagesVisibilityDepth == NO) {
    _visibilityDepth = 0;
    [self visibilityDepthDidChange];
  }
}

ASVisibilityViewDidDisappearImplementation;

ASVisibilityDepthImplementation;

- (void)visibilityDepthDidChange
{
  ASLayoutRangeMode rangeMode = ASLayoutRangeModeForVisibilityDepth(self.visibilityDepth);
#if AS_LOG_VISIBILITY_CHANGES
  NSString *rangeModeString;
  switch (rangeMode) {
    case ASLayoutRangeModeMinimum:
      rangeModeString = @"Minimum";
      break;
      
    case ASLayoutRangeModeFull:
      rangeModeString = @"Full";
      break;
      
    case ASLayoutRangeModeVisibleOnly:
      rangeModeString = @"Visible Only";
      break;
      
    case ASLayoutRangeModeLowMemory:
      rangeModeString = @"Low Memory";
      break;
      
    default:
      break;
  }
  NSLog(@"Updating visibility of:%@ to: %@ (visibility depth: %d)", self, rangeModeString, self.visibilityDepth);
#endif
  [self updateCurrentRangeModeWithModeIfPossible:rangeMode];
}

#pragma mark - Automatic range mode

- (BOOL)automaticallyAdjustRangeModeBasedOnViewEvents
{
  return _automaticallyAdjustRangeModeBasedOnViewEvents;
}

- (void)setAutomaticallyAdjustRangeModeBasedOnViewEvents:(BOOL)automaticallyAdjustRangeModeBasedOnViewEvents
{
  _automaticallyAdjustRangeModeBasedOnViewEvents = automaticallyAdjustRangeModeBasedOnViewEvents;
}

- (void)updateCurrentRangeModeWithModeIfPossible:(ASLayoutRangeMode)rangeMode
{
  if (!_automaticallyAdjustRangeModeBasedOnViewEvents) { return; }
  if (![_node conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)]) {
    return;
  }

  id<ASRangeControllerUpdateRangeProtocol> updateRangeNode = (id<ASRangeControllerUpdateRangeProtocol>)_node;
  [updateRangeNode updateCurrentRangeWithMode:rangeMode];
}

#pragma mark - Layout Helpers

- (ASSizeRange)nodeConstrainedSize
{
  CGSize viewSize = self.view.bounds.size;
  return ASSizeRangeMake(viewSize, viewSize);
}

- (ASInterfaceState)interfaceState
{
  return _node.interfaceState;
}

@end