Question

I have a UITableView within a UIScrollView. It took me quite a lot of work to make it work.

The tableView is 640×350, I use the scroll view to scroll from one end of the cell to the next.
The scroll view is 320×350.
The scroll view’s content size is 640×350

I’m running into this problem:
if I set scrollView’s minimum zoom scale to 0.5, the tableview’s width now fills the screen, but it’s height is only half the screen. I would like the tableview to show more rows when I zoom out to 0.5.

First of all I would like to understand if this is the correct behavior, or the result of my tableView’s content size and frame manipulations. The tableview has all springs and struts set in interface builder and should fill the frame available. This is my first attempt at zooming in months, and I don’t remember how it works with zooming.

Can someone help me understand where and what do I need to adjust?

As far as I understand, I need to put the code into scrollViewDidZoom: that will manipulate the tableView’s frame and content size.

PS. I”m returning the tableview from the viewForZooming: method of UIScrollView

Answer 1

What you are trying to achieve is pretty hard.

Solution 1 This solution uses the exact setup you have (UITableView inside UIScrollView).

You say that when you set the zoomScale to 0.5, you want your table view to fill the scrollView vertically. At 0.5, your table view must be 640×700 in order to fill the UIScrollView as you wish. For this to happen, on scrollViewDidZoom: you must resize the frame of the table view to 640×700

- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    // No matter what the zoomScale is, the tableView will be zoomed accordingly
    // Only zoom the height of the table
    tableView.frame = CGRectMake(0, 0, 640, 350 / zoomScale);

    // Also, update the contentSize
    scrollView.contentSize = CGSizeMake(640, 350 / zoomScale);
}

If you run the code above for zoomScale = 0.5 you will get a frame size of 640×700.

This only changes the frame of the table and doesn’t change the heights of the cells. This means that as you zoom out, you will also see more cells in the tableview.

Solution 2 Use only UITableView

UITableView is a subclass of UIScrollView. This means it has the ability to zoom and scroll around.

Start with a UITableView with the size that you want on the screen. Then, after the content is loaded modify the contentSize and make it wider than your frame width. This should enable horizontal scrolling.

However, UITableViewCells have their frame set automatically to the width of the tableview frame. You can bypass this by using a custom UITableViewCell, with clipsToBounds=false. Inside it you will insert a UIView with the frame set to the width&height you desire and with no autoresizingMask. When the tableview will resize UITableViewCell frame, this will not affect your inner UIView.