CGImage that has already been rotated to the right orientation.
This returns a thumbnail image representing the asset. The thumbnail returned will preserve the original aspect ration of the original image returned by the AssetsLibrary.ALAssetRepresentation.ALAssetRepresentation.GetImage(). The image will be rendered in the correct orientation, so it is not necessary to apply any rotation on the returned value.
This API is only available on iOS 5. On previous version of the operating system you can obtain a square thumbnail by using the ALAsset.Thumbnail property.