Horizontal UIScrollView inside a UITableViewCell

I have found a workaround.

Recreating from scratch a very simple UITableView (8 rows), and inserting a UIScrollView in just the second row, works perfectly. Nested scroll views (the TableView and the ScrollView) scroll independently as expected. All that was done in a single-file test project, in the AppDelegate.

So… first I thought “this might be a delegation problem”, so I told the scrollView that its delegate was the TableView, not my custom TableViewCell subclass. To no avail.

Then instead of resorting to a custom, clean TableViewCell subclass that just adds the ScrollView and the PageControl, I resorted to creating a plain TableViewCell in the TableView’s cellForRowAtIndexPath: method. Then, I create a UIScrollView right after initializing the TableViewCell, then add it to the TableViewCell, and shazam… it works!

Before:

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kVolumePreviewCellIdentifier];
if (cell == nil) {
    cell = [[[phVolumePreviewCell alloc] init] autorelease];
}

[(phVolumePreviewCell *)cell setVolume:volume];
// That does the job of creating the cell's scrollView and pageControl

return (UITableViewCell *)cell

After:

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kvcPreviewRowIdentifier];
if (cell == nil) {
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:kvcPreviewRowIdentifier] autorelease];

    previewScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, tableView.frame.size.width, kvcPreviewScrollViewHeight)];
    [previewScrollView setContentSize:CGSizeMake(1000, kvcPreviewScrollViewHeight)];
    [[cell contentView] addSubview:previewScrollView];

    previewPageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(0, kvcPreviewScrollViewHeight, tableView.frame.size.width, kvcPreviewPageControlHeight)];
    [previewPageControl setNumberOfPages:4];
    [[cell contentView] addSubview:previewPageControl];
}

return (UITableViewCell *)cell;

How the heck comes that when I create my scrollView from the TVCell subclass, it doesn’t play nice ; but when I create the scrollView from the TableView right after creating a “classical” TVCell, it works?

I might have found a solution, but I’m still puzzled by the reason.