3.4.0 - Spring is here

Add

• Use the onlyLoadFirstFrame option to load only the first frame from a GIF file. It will be useful when you want to display a static preview of the first frame from a GIF image. By doing so, you could save huge ammount of memory. #591

Fix

• Now cancel on a RetrieveImageTask will work properly even when the downloading not started for UIButton and NSButton too. #580
• Progress block of extensions setting methods will not be called multiple times if you set another task while the previous one still in downloading. #583
• Image cache will work properly when ImagePrefetcher trying to prefetch images with an ImageProcessor. Now the fetched and processed images could be retrieved correctly. #590