iPhone Table View with Expand and Collapsed

I came across similar feature, to build it a rough algorithm will be:

1. implement the uitableviewdelgate and uitableviewdatasource protocols

2. create a global variable expandedSectionIndex = -1;
= -1 represents all collapsed.
>= 0 represents expandedSectionIndex.

//the following protocol definitions will take care of which section is to be expanded.

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
if(expandedSectionIndex == section) return [self.dataArray[section] count];
else return 0;
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView [
if(self.dataArray)return [self.dataArray count]; 
}

2. define custom header views in – tableView:viewForHeaderInSection:
- buttons having frame equivalent to header view frame
- set button tag property with value of section number.
- associate all buttons with selector - (void)expand:(id) sender;

// this event will select the expanded section
- (void)expand:(id) sender {
expandedSectionIndex = [sender tag];
[self.tableView reload];
}

[edit]code block added[/edit]