How to get Size of UIImage in Bytes in iOS 4.0+?

I am trying to pick an image from the photo library or from the camera.
The delegate method:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo

Gives me the UIImage object. I need to find the size of the image in bytes for my application.

Is there any way I can get the file type of the image and also the size in the bytes?

Any kind of help would be highly appreciated.

Thanks in advance