Adding #import for CoreGraphics

AFNetworking/AFImageRequestOperation.m

@@ -33,6 +33,8 @@ static dispatch_queue_t image_request_operation_processing_queue() {
 }
 
 #if defined(__IPHONE_OS_VERSION_MIN_REQUIRED)
+#import <CoreGraphics/CoreGraphics.h>
+
 static UIImage * AFInflatedImageFromResponseWithDataAtScale(NSHTTPURLResponse *response, NSData *data, CGFloat scale) {
     if (!data || [data length] == 0) {
         return nil;