IKImageBrowserView inside padding

I'm customizing an IKImageBrowserView and I would like to change the space between cells.

I'm using this method [_imageBrowser setIntercellSpacing:NSMakeSize(0, 0)] to set the spacing between cells to 0 pixels and it works.

But I notice an inside padding of 10 pixels in the IKImageBrowserView :

Any Idea?