UITableView top and button separator inset not working

I'm trying to set insets in my tableview so that each cell does not stick to each other.

To do this, I've added the following method to my tableView:willDisplayCell:forRowAtIndexPath:

if([tableView respondsToSelector:@selector(setSeparatorInset:)]){
    [tableView setSeparatorInset:UIEdgeInsetsMake(10, 15, 10, 15)];
}

I basically want a 10pt space on the top and bottom of the cell, before the next cell. This code partially works, because there is a visible 15pt inset on the left and right. However, the top and bottom are still connected.

Thanks!

~Carpetfizz