¿Cómo obtener un NSDATE de UIImage?

¿Cómo obtengo una fecha o metadatos de un UIImage en este caso:

//UIImagePickerControllerSourceType
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

//delegate return
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{

// po info in console -> there is no metadata of the image where i can find the date
// Has anyone an idea how to get it?

}