How to implement an accordion view for an iPhone SDK app?

Question

Has anyone seen an implementation of an "accordion" (maybe called "animated outline") view for the iPhone? I found an example project for Cocoa, but before trying a port, I was hoping that someone has invented the wheel already.

To make it clear, in a UIView, consider a stack of sections, each containing a header, and then some contents. When the user touches the header (or through some message/event), if the section is already open => close it; if the section is closed => open it and close any other open section. An example in jQuery looks like: http://docs.jquery.com/UI/Accordion

In my case, I'd want to be able to put any UIView contents in each section.

I'd be interested in just seeing some real apps who have implemented this - just to know it's possible!

Answer 1

I would just use a UITableView, make each cell's height depend on whether or not it's "open" and then go from there. It's easy to resize the rows and you could just make the total height for the combined cells be the available height in the UITableView so that it looks like an accordion more than just a table.

This is a quick hack that should work, but in your UITableViewController subclass's .h file:

bool sectionopen[4]; ///or some other way of storing the sections expanded/closed state

And in the .m file put something like:

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return 4;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath  {
    if (sectionopen[indexPath.row]) {
        return 240;///it's open
    } else {
        return 45;///it's closed
    }

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *mycell = [[[UITableViewCell alloc] init] autorelease];
    mycell.textLabel.text= @"Section Name";
    return mycell;
}


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    ///turn them all off
    sectionopen[0]=NO;
    sectionopen[1]=NO;
    sectionopen[2]=NO;
    sectionopen[3]=NO;

    ///open this one
    sectionopen[indexPath.row]=YES;

    ///animate the opening and expand the row
    [self.tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationFade];
}

This will basically take 4 rows and turn them into collapsable sections where selecting one row will expand it to 240 pixels and collapse all other rows to 40. You can change all of those numbers and figure out the sections and do whatever else you'd like with it.

I've tried this out and it works. You can then complete it by adding the other content to your cell creation code to add whatever you'd like to a section (including possibly a scrolling UITextView if you'd like).