[Examples] Move several simpler, single-purpose examples to extras to ensure Travis does not time out.

examples_extra/Multiplex/Sample/ScreenNode.m

@@ -0,0 +1,158 @@
+//
+//  ScreenNode.m
+//  Sample
+//
+//  Created by Huy Nguyen on 16/09/15.
+//  Copyright (c) 2015 Facebook. All rights reserved.
+//
+
+#import "ScreenNode.h"
+
+@interface ScreenNode() <ASMultiplexImageNodeDataSource, ASMultiplexImageNodeDelegate, ASImageDownloaderProtocol>
+@end
+
+@implementation ScreenNode
+
+- (instancetype)init
+{
+  if (!(self = [super init])) {
+    return nil;
+  }
+
+  // multiplex image node!
+  // NB:  we're using a custom downloader with an artificial delay for this demo, but ASPINRemoteImageDownloader works too!
+  _imageNode = [[ASMultiplexImageNode alloc] initWithCache:nil downloader:self];
+  _imageNode.dataSource = self;
+  _imageNode.delegate = self;
+  
+  // placeholder colour
+  _imageNode.backgroundColor = ASDisplayNodeDefaultPlaceholderColor();
+  
+  // load low-quality images before high-quality images
+  _imageNode.downloadsIntermediateImages = YES;
+  
+  // simple status label.  Synchronous to avoid flicker / placeholder state when updating.
+  _buttonNode = [[ASButtonNode alloc] init];
+  [_buttonNode addTarget:self action:@selector(reload) forControlEvents:ASControlNodeEventTouchUpInside];
+  _buttonNode.titleNode.displaysAsynchronously = NO;
+  
+  [self addSubnode:_imageNode];
+  [self addSubnode:_buttonNode];
+  
+  return self;
+}
+
+- (void)start
+{
+  [self setText:@"loading…"];
+  _buttonNode.userInteractionEnabled = NO;
+  _imageNode.imageIdentifiers = @[ @"best", @"medium", @"worst" ]; // go!
+}
+
+- (void)reload
+{
+  [self start];
+  [_imageNode reloadImageIdentifierSources];
+}
+
+- (void)setText:(NSString *)text
+{
+  NSDictionary *attributes = @{NSFontAttributeName: [UIFont fontWithName:@"HelveticaNeue-Light" size:22.0f]};
+  NSAttributedString *string = [[NSAttributedString alloc] initWithString:text
+                                                               attributes:attributes];
+  [_buttonNode setAttributedTitle:string forState:ASControlStateNormal];
+  [self setNeedsLayout];
+}
+
+- (ASLayoutSpec *)layoutSpecThatFits:(ASSizeRange)constrainedSize
+{
+  ASRatioLayoutSpec *imagePlaceholder = [ASRatioLayoutSpec ratioLayoutSpecWithRatio:1 child:_imageNode];
+  
+  ASStackLayoutSpec *verticalStack = [[ASStackLayoutSpec alloc] init];
+  verticalStack.direction = ASStackLayoutDirectionVertical;
+  verticalStack.spacing = 10;
+  verticalStack.justifyContent = ASStackLayoutJustifyContentCenter;
+  verticalStack.alignItems = ASStackLayoutAlignItemsCenter;
+  verticalStack.children = @[imagePlaceholder, _buttonNode];
+                                      
+  return [ASInsetLayoutSpec insetLayoutSpecWithInsets:UIEdgeInsetsMake(10, 10, 10, 10) child:verticalStack];
+}
+
+#pragma mark -
+#pragma mark ASMultiplexImageNode data source & delegate.
+
+- (NSURL *)multiplexImageNode:(ASMultiplexImageNode *)imageNode URLForImageIdentifier:(id)imageIdentifier
+{
+  if ([imageIdentifier isEqualToString:@"worst"]) {
+    return [NSURL URLWithString:@"https://raw.githubusercontent.com/facebook/AsyncDisplayKit/master/examples/Multiplex/worst.png"];
+  }
+  
+  if ([imageIdentifier isEqualToString:@"medium"]) {
+    return [NSURL URLWithString:@"https://raw.githubusercontent.com/facebook/AsyncDisplayKit/master/examples/Multiplex/medium.png"];
+  }
+  
+  if ([imageIdentifier isEqualToString:@"best"]) {
+    return [NSURL URLWithString:@"https://raw.githubusercontent.com/facebook/AsyncDisplayKit/master/examples/Multiplex/best.png"];
+  }
+  
+  // unexpected identifier
+  return nil;
+}
+
+- (void)multiplexImageNode:(ASMultiplexImageNode *)imageNode didFinishDownloadingImageWithIdentifier:(id)imageIdentifier error:(NSError *)error
+{
+  [self setText:[NSString stringWithFormat:@"loaded '%@'", imageIdentifier]];
+  
+  if ([imageIdentifier isEqualToString:@"best"]) {
+    [self setText:[_buttonNode.titleNode.attributedString.string stringByAppendingString:@".  tap to reload"]];
+    _buttonNode.userInteractionEnabled = YES;
+  }
+}
+
+
+#pragma mark -
+#pragma mark ASImageDownloaderProtocol.
+
+- (id)downloadImageWithURL:(NSURL *)URL
+             callbackQueue:(dispatch_queue_t)callbackQueue
+     downloadProgressBlock:(void (^)(CGFloat progress))downloadProgressBlock
+                completion:(void (^)(CGImageRef image, NSError *error))completion
+{
+  // if no callback queue is supplied, run on the main thread
+  if (callbackQueue == nil) {
+    callbackQueue = dispatch_get_main_queue();
+  }
+  
+  // call completion blocks
+  void (^handler)(NSURLResponse *, NSData *, NSError *) = ^(NSURLResponse *response, NSData *data, NSError *connectionError) {
+    // add an artificial delay
+    usleep(1.0 * USEC_PER_SEC);
+    
+    // ASMultiplexImageNode callbacks
+    dispatch_async(callbackQueue, ^{
+      if (downloadProgressBlock) {
+        downloadProgressBlock(1.0f);
+      }
+      
+      if (completion) {
+        completion([[UIImage imageWithData:data] CGImage], connectionError);
+      }
+    });
+  };
+  
+  // let NSURLConnection do the heavy lifting
+  NSURLRequest *request = [NSURLRequest requestWithURL:URL];
+  [NSURLConnection sendAsynchronousRequest:request
+                                     queue:[[NSOperationQueue alloc] init]
+                         completionHandler:handler];
+  
+  // return nil, don't support cancellation
+  return nil;
+}
+
+- (void)cancelImageDownloadForIdentifier:(id)downloadIdentifier
+{
+  // no-op, don't support cancellation
+}
+
+@end