diff --git a/AsyncDisplayKit/ASMultiplexImageNode.h b/AsyncDisplayKit/ASMultiplexImageNode.h
index eb01209dfd..6780a3513d 100644
--- a/AsyncDisplayKit/ASMultiplexImageNode.h
+++ b/AsyncDisplayKit/ASMultiplexImageNode.h
@@ -130,7 +130,7 @@ typedef NS_ENUM(NSUInteger, ASMultiplexImageNodeErrorCode) {
  
  * @see `+[NSURL URLWithAssetLocalIdentifier:targetSize:contentMode:options:]` below.
  */
-@property (nonatomic, strong) PHImageManager *imageManager;
+@property (nullable, nonatomic, strong) PHImageManager *imageManager;
 #endif
 @end
 
diff --git a/AsyncDisplayKit/Details/ASImageProtocols.h b/AsyncDisplayKit/Details/ASImageProtocols.h
index 6b86fb97db..ff6803bd8d 100644
--- a/AsyncDisplayKit/Details/ASImageProtocols.h
+++ b/AsyncDisplayKit/Details/ASImageProtocols.h
@@ -61,7 +61,16 @@ typedef void(^ASImageCacherCompletion)(id <ASImageContainerProtocol> _Nullable i
 
 @end
 
+/**
+ @param image The image that was downloaded, if the image could be successfully downloaded; nil otherwise.
+ @param error An error describing why the download of `URL` failed, if the download failed; nil otherwise.
+ @param downloadIdentifier The identifier for the download task that completed.
+ */
 typedef void(^ASImageDownloaderCompletion)(id <ASImageContainerProtocol> _Nullable image, NSError * _Nullable error, id _Nullable downloadIdentifier);
+
+/**
+ @param progress The progress of the download, in the range of (0.0, 1.0), inclusive.
+ */
 typedef void(^ASImageDownloaderProgress)(CGFloat progress);
 typedef void(^ASImageDownloaderProgressImage)(UIImage *progressImage, CGFloat progress, id _Nullable downloadIdentifier);
 
@@ -98,10 +107,7 @@ typedef NS_ENUM(NSUInteger, ASImageDownloaderPriority) {
  @param URL The URL of the image to download.
  @param callbackQueue The queue to call `downloadProgressBlock` and `completion` on.
  @param downloadProgress The block to be invoked when the download of `URL` progresses.
- @param progress The progress of the download, in the range of (0.0, 1.0), inclusive.
  @param completion The block to be invoked when the download has completed, or has failed.
- @param image The image that was downloaded, if the image could be successfully downloaded; nil otherwise.
- @param error An error describing why the download of `URL` failed, if the download failed; nil otherwise.
  @discussion This method is likely to be called on the main thread, so any custom implementations should make sure to background any expensive download operations.
  @result An opaque identifier to be used in canceling the download, via `cancelImageDownloadForIdentifier:`. You must
  retain the identifier if you wish to use it later.
@@ -109,7 +115,7 @@ typedef NS_ENUM(NSUInteger, ASImageDownloaderPriority) {
 - (nullable id)downloadImageWithURL:(NSURL *)URL
                       callbackQueue:(dispatch_queue_t)callbackQueue
                    downloadProgress:(nullable ASImageDownloaderProgress)downloadProgress
-                         completion:(nullable ASImageDownloaderCompletion)completion;
+                         completion:(ASImageDownloaderCompletion)completion;
 
 
 /**
diff --git a/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.h b/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.h
index 12c6b27376..a1238272ed 100644
--- a/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.h
+++ b/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.h
@@ -9,8 +9,12 @@
 #import <Foundation/Foundation.h>
 #import "ASImageProtocols.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface ASPINRemoteImageDownloader : NSObject <ASImageCacheProtocol, ASImageDownloaderProtocol>
 
-+ (instancetype)sharedDownloader;
++ (ASPINRemoteImageDownloader *)sharedDownloader;
 
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.m b/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.m
index 401211709c..ee78b0e7b6 100644
--- a/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.m
+++ b/AsyncDisplayKit/Details/ASPINRemoteImageDownloader.m
@@ -96,8 +96,9 @@
 
 - (id <ASImageContainerProtocol>)synchronouslyFetchedCachedImageWithURL:(NSURL *)URL;
 {
-  NSString *key = [[self sharedPINRemoteImageManager] cacheKeyForURL:URL processorKey:nil];
-  PINRemoteImageManagerResult *result = [[self sharedPINRemoteImageManager] synchronousImageFromCacheWithCacheKey:key options:PINRemoteImageManagerDownloadOptionsSkipDecode];
+  PINRemoteImageManager *manager = [self sharedPINRemoteImageManager];
+  NSString *key = [manager cacheKeyForURL:URL processorKey:nil];
+  PINRemoteImageManagerResult *result = [manager synchronousImageFromCacheWithCacheKey:key options:PINRemoteImageManagerDownloadOptionsSkipDecode];
 #if PIN_ANIMATED_AVAILABLE
   if (result.alternativeRepresentation) {
     return result.alternativeRepresentation;
@@ -133,7 +134,18 @@
                    downloadProgress:(ASImageDownloaderProgress)downloadProgress
                          completion:(ASImageDownloaderCompletion)completion;
 {
-  return [[self sharedPINRemoteImageManager] downloadImageWithURL:URL options:PINRemoteImageManagerDownloadOptionsSkipDecode completion:^(PINRemoteImageManagerResult *result) {
+  return [[self sharedPINRemoteImageManager] downloadImageWithURL:URL options:PINRemoteImageManagerDownloadOptionsSkipDecode progressDownload:^(int64_t completedBytes, int64_t totalBytes) {
+    if (downloadProgress == nil) { return; }
+    
+    /// If we're targeting the main queue and we're on the main thread, call immediately.
+    if (ASDisplayNodeThreadIsMain() && callbackQueue == dispatch_get_main_queue()) {
+      downloadProgress(totalBytes / (CGFloat)completedBytes);
+    } else {
+      dispatch_async(callbackQueue, ^{
+        downloadProgress(totalBytes / (CGFloat)completedBytes);
+      });
+    }
+  } completion:^(PINRemoteImageManagerResult * _Nonnull result) {
     /// If we're targeting the main queue and we're on the main thread, complete immediately.
     if (ASDisplayNodeThreadIsMain() && callbackQueue == dispatch_get_main_queue()) {
 #if PIN_ANIMATED_AVAILABLE