How to properly set "Mode" for laying out controls on a UIScrollView

Question

I have a UIScrollView with 5 controls on it like so:

[UIButton1] [UIButton2]

[UITableView1]

[UIButton3][UiButton4]

What I would like to be able to do is to adjust the UIScrollView size, and have the contents lay out properly with the top buttons at the top, bottom buttons at the bottom, and the table view sizing to take up the middle.

I just can't find a decent explanation of what the various Mode settings do for layout.

The method I am using to adjust the scroll view is:

myScrollView setFrame:CGRectMake(0,0,320,480)

or

myScrollView setFrame:CGRectMake(0,0,320,440)