[Issue #103] Adding imageScale property on AFImageRequestOperation, to allow override of default behavior on iOS to automatically scale images for retina displays

AFNetworking/AFImageRequestOperation.h

@@ -53,14 +53,27 @@
 @private
 #if __IPHONE_OS_VERSION_MIN_REQUIRED
     UIImage *_responseImage;
+    CGFloat _imageScale;
 #elif __MAC_OS_X_VERSION_MIN_REQUIRED
     NSImage *_responseImage;
 #endif
 }
 
 #if __IPHONE_OS_VERSION_MIN_REQUIRED
+/**
+ An image constructed from the response data. If an error occurs during the request, `nil` will be returned, and the `error` property will be set to the error.
+ */
 @property (readonly, nonatomic, retain) UIImage *responseImage;
+
+/**
+ The scale factor used when interpreting the image data to construct `responseImage`. Specifying a scale factor of 1.0 results in an image whose size matches the pixel-based dimensions of the image. Applying a different scale factor changes the size of the image as reported by the size property. This is set to the value of `[[UIScreen mainScreen] scale]` by default, which automatically scales images for retina displays, for instance.
+ */
+@property (nonatomic, assign) CGFloat imageScale;
 #elif __MAC_OS_X_VERSION_MIN_REQUIRED
+
+/**
+ An image constructed from the response data. If an error occurs during the request, `nil` will be returned, and the `error` property will be set to the error.
+ */
 @property (readonly, nonatomic, retain) NSImage *responseImage;
 #endif
 

AFNetworking/AFImageRequestOperation.m

@@ -45,6 +45,9 @@ static dispatch_queue_t image_request_operation_processing_queue() {
 
 @implementation AFImageRequestOperation
 @synthesize responseImage = _responseImage;
+#if __IPHONE_OS_VERSION_MIN_REQUIRED
+@synthesize imageScale = _imageScale;
+#endif
 
 #if __IPHONE_OS_VERSION_MIN_REQUIRED
 + (AFImageRequestOperation *)imageRequestOperationWithRequest:(NSURLRequest *)urlRequest                
@@ -173,6 +176,10 @@ static dispatch_queue_t image_request_operation_processing_queue() {
     
     self.acceptableContentTypes = [[self class] defaultAcceptableContentTypes];
     
+#if __IPHONE_OS_VERSION_MIN_REQUIRED
+    self.imageScale = [[UIScreen mainScreen] scale];
+#endif
+    
     return self;
 }
 
@@ -184,16 +191,24 @@ static dispatch_queue_t image_request_operation_processing_queue() {
 #if __IPHONE_OS_VERSION_MIN_REQUIRED
 - (UIImage *)responseImage {
     if (!_responseImage && [self isFinished]) {
-        if ([[UIScreen mainScreen] scale] == 2.0) {
         CGImageRef imageRef = [[UIImage imageWithData:self.responseData] CGImage];
-            self.responseImage = [UIImage imageWithCGImage:imageRef scale:2.0 orientation:UIImageOrientationUp];
+        self.responseImage = [UIImage imageWithCGImage:imageRef scale:self.imageScale orientation:UIImageOrientationUp];
-        } else {
-            self.responseImage = [UIImage imageWithData:self.responseData]; 
-        }
     }
     
     return _responseImage;
 }
+
+- (void)setImageScale:(CGFloat)imageScale {
+    if (imageScale == _imageScale) {
+        return;
+    }
+    
+    [self willChangeValueForKey:@"imageScale"];
+    _imageScale = imageScale;
+    [self didChangeValueForKey:@"imageScale"];
+    
+    self.responseImage = nil;
+}
 #elif __MAC_OS_X_VERSION_MIN_REQUIRED 
 - (NSImage *)responseImage {
     if (!_responseImage && [self isFinished]) {