API to cancel loading an image

Author: Mallory Paine

FastImageCache/FICImageCache.h

@@ -162,6 +162,8 @@ typedef void (^FICImageRequestCompletionBlock)(UIImage *sourceImage);
  */
 - (void)deleteImageForEntity:(id <FICEntity>)entity withFormatName:(NSString *)formatName;
 
+- (void)cancelImageRetrievalForEntity:(id <FICEntity>)entity withFormatName:(NSString *)formatName;
+    
 ///-----------------------------------
 /// @name Checking for Image Existence
 ///-----------------------------------
@@ -227,6 +229,9 @@ typedef void (^FICImageRequestCompletionBlock)(UIImage *sourceImage);
 
 @optional
 
+- (void)imageCache:(FICImageCache *)imageCache cancelImageLoadingForEntity:(id <FICEntity>)entity withFormatName:(NSString *)formatName;
+
+
 /**
  This method is called on the delegate to determine whether or not all formats in a family should be processed right now.
  

FastImageCache/FICImageCache.m

@@ -29,6 +29,7 @@ @interface FICImageCache () {
 
     BOOL _delegateImplementsShouldProcessAllFormatsInFamilyForEntity;
     BOOL _delegateImplementsErrorDidOccurWithMessage;
+    BOOL _delegateImplementsCancelImageLoadingForEntityWithFormatName;
 }
 
 @end
@@ -47,6 +48,7 @@ - (void)setDelegate:(id<FICImageCacheDelegate>)delegate {
 
         _delegateImplementsShouldProcessAllFormatsInFamilyForEntity = [_delegate respondsToSelector:@selector(imageCache:shouldProcessAllFormatsInFamily:forEntity:)];
         _delegateImplementsErrorDidOccurWithMessage = [_delegate respondsToSelector:@selector(imageCache:errorDidOccurWithMessage:)];
+        _delegateImplementsCancelImageLoadingForEntityWithFormatName = [_delegate respondsToSelector:@selector(imageCache:cancelImageLoadingForEntity:withFormatName:)];
     }
 }
 
@@ -369,6 +371,31 @@ - (void)deleteImageForEntity:(id <FICEntity>)entity withFormatName:(NSString *)f
     [imageTable saveMetadata];
 }
 
+- (void)cancelImageRetrievalForEntity:(id <FICEntity>)entity withFormatName:(NSString *)formatName {
+    NSURL *sourceImageURL = [entity sourceImageURLWithFormatName:formatName];
+    NSMutableDictionary *requestDictionary = [_requests objectForKey:sourceImageURL];
+    if (requestDictionary) {
+        NSString *entityUUID = [entity UUID];
+        NSMutableDictionary *entityRequestsDictionary = [requestDictionary objectForKey:entityUUID];
+        if (entityRequestsDictionary) {
+            NSMutableDictionary *completionBlocksDictionary = [entityRequestsDictionary objectForKey:FICImageCacheCompletionBlocksKey];
+            [completionBlocksDictionary removeObjectForKey:formatName];
+            
+            if ([completionBlocksDictionary count] == 0) {
+                [requestDictionary removeObjectForKey:entityUUID];
+            }
+            
+            if ([requestDictionary count] == 0) {
+                [_requests removeObjectForKey:sourceImageURL];
+                
+                if (_delegateImplementsCancelImageLoadingForEntityWithFormatName) {
+                    [_delegate imageCache:self cancelImageLoadingForEntity:entity withFormatName:formatName];
+                }
+            }
+        }
+    }
+}
+
 - (void)reset {
     for (FICImageTable *imageTable in [_imageTables allValues]) {
         [imageTable reset];