Added failureBlock to allow proper handing of errors situations

Author: Brendt

JMImageCache.h

@@ -22,8 +22,8 @@
 
 + (JMImageCache *) sharedCache;
 
-- (void) imageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion;
-- (void) imageForURL:(NSURL *)url completionBlock:(void (^)(UIImage *image))completion;
+- (void) imageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure;
+- (void) imageForURL:(NSURL *)url completionBlock:(void (^)(UIImage *image))completion failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure;
 
 - (UIImage *) cachedImageForKey:(NSString *)key;
 - (UIImage *) cachedImageForURL:(NSURL *)url;

JMImageCache.m

@@ -31,7 +31,7 @@ @interface JMImageCache ()
 
 @property (strong, nonatomic) NSOperationQueue *diskOperationQueue;
 
-- (void) _downloadAndWriteImageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion;
+- (void) _downloadAndWriteImageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure;
 
 @end
 
@@ -60,33 +60,58 @@ - (id) init {
 	return self;
 }
 
-- (void) _downloadAndWriteImageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion {
+- (void) _downloadAndWriteImageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure
+{
     if (!key && !url) return;
 
     if (!key) {
         key = keyForURL(url);
     }
 
     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
-        NSData *data = [NSData dataWithContentsOfURL:url];
-        UIImage *i = [[UIImage alloc] initWithData:data];
-        // stop process if the method could not initialize the image from the specified data
-        if (!i) return;
 
-        NSString *cachePath = cachePathForKey(key);
-        NSInvocation *writeInvocation = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:@selector(writeData:toPath:)]];
-
-        [writeInvocation setTarget:self];
-        [writeInvocation setSelector:@selector(writeData:toPath:)];
-        [writeInvocation setArgument:&data atIndex:2];
-        [writeInvocation setArgument:&cachePath atIndex:3];
-
-        [self performDiskWriteOperation:writeInvocation];
-        [self setImage:i forKey:key];
-
-        dispatch_async(dispatch_get_main_queue(), ^{
-            if(completion) completion(i);
-        });
+        NSURLRequest* request = [NSURLRequest requestWithURL:url];
+        NSURLResponse* response = nil;
+        NSError* error = nil;
+        NSData* data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
+        
+        if (error)
+        {
+            dispatch_async(dispatch_get_main_queue(), ^{
+                
+                if(failure)  failure(request, response, error);
+            });
+            return;
+        }
+        
+        UIImage *i = [[UIImage alloc] initWithData:data];
+        if (!i)
+        {
+            NSMutableDictionary *errorDetail = [NSMutableDictionary dictionary];
+            [errorDetail setValue:[NSString stringWithFormat:@"Failed to init image with data from for URL: %@", url] forKey:NSLocalizedDescriptionKey];
+            NSError* error = [NSError errorWithDomain:@"JMImageCacheErrorDomain" code:1 userInfo:errorDetail];
+            dispatch_async(dispatch_get_main_queue(), ^{
+                
+                if(failure) failure(request, response, error);
+            });
+        }
+        else
+        {
+            NSString *cachePath = cachePathForKey(key);
+            NSInvocation *writeInvocation = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:@selector(writeData:toPath:)]];
+            
+            [writeInvocation setTarget:self];
+            [writeInvocation setSelector:@selector(writeData:toPath:)];
+            [writeInvocation setArgument:&data atIndex:2];
+            [writeInvocation setArgument:&cachePath atIndex:3];
+            
+            [self performDiskWriteOperation:writeInvocation];
+            [self setImage:i forKey:key];
+            
+            dispatch_async(dispatch_get_main_queue(), ^{
+                if(completion) completion(i);
+            });
+        }
     });
 }
 
@@ -131,19 +156,19 @@ - (void) removeObjectForKey:(id)key {
 #pragma mark -
 #pragma mark Getter Methods
 
-- (void) imageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion {
+- (void) imageForURL:(NSURL *)url key:(NSString *)key completionBlock:(void (^)(UIImage *image))completion failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure{
 
 	UIImage *i = [self cachedImageForKey:key];
 
 	if(i) {
 		if(completion) completion(i);
 	} else {
-        [self _downloadAndWriteImageForURL:url key:key completionBlock:completion];
+        [self _downloadAndWriteImageForURL:url key:key completionBlock:completion failureBlock:failure];
     }
 }
 
-- (void) imageForURL:(NSURL *)url completionBlock:(void (^)(UIImage *image))completion {
-    [self imageForURL:url key:keyForURL(url) completionBlock:completion];
+- (void) imageForURL:(NSURL *)url completionBlock:(void (^)(UIImage *image))completion failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure{
+    [self imageForURL:url key:keyForURL(url) completionBlock:completion failureBlock:(failure)];
 }
 
 - (UIImage *) cachedImageForKey:(NSString *)key {
@@ -185,7 +210,8 @@ - (UIImage *) imageForURL:(NSURL *)url key:(NSString*)key delegate:(id<JMImageCa
                     [d cache:self didDownloadImage:image forURL:url key:key];
                 }
             }
-        }];
+        }
+        failureBlock:nil];
     }
 
     return nil;

UIImageView+JMImageCache.h

@@ -13,7 +13,10 @@
 - (void) setImageWithURL:(NSURL *)url;
 - (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage;
 - (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *))completionBlock;
+- (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *))completionBlock failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure;
 - (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage;
 - (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *image))completionBlock;
+- (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *image))completionBlock failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failure;
+
 
 @end

UIImageView+JMImageCache.m

@@ -44,12 +44,18 @@ - (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage {
     [self setImageWithURL:url key:nil placeholder:placeholderImage];
 }
 - (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *))completionBlock {
-    [self setImageWithURL:url key:nil placeholder:placeholderImage completionBlock:completionBlock];
+    [self setImageWithURL:url key:nil placeholder:placeholderImage completionBlock:completionBlock failureBlock:nil];
+}
+- (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *))completionBlock failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failureBlock {
+    [self setImageWithURL:url key:nil placeholder:placeholderImage completionBlock:completionBlock failureBlock:failureBlock];
 }
 - (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage {
     [self setImageWithURL:url key:key placeholder:placeholderImage completionBlock:nil];
 }
 - (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *image))completionBlock {
+    [self setImageWithURL:url key:key placeholder:placeholderImage completionBlock:completionBlock];
+}
+- (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage completionBlock:(void (^)(UIImage *image))completionBlock failureBlock:(void (^)(NSURLRequest *request, NSURLResponse *response, NSError* error))failureBlock{
     self.jm_imageURL = url;
     self.image = placeholderImage;
 
@@ -101,6 +107,10 @@ - (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)
                         if (completionBlock) completionBlock(image);
                     });
                 }
+            }
+            failureBlock:^(NSURLRequest *request, NSURLResponse *response, NSError* error)
+            {
+                if (failureBlock) failureBlock(request, response, error);
             }];
         }
     });