Expandable tableview Logic in iOS

Ans : 

Logic  : 

• Display UITableView containing just the header/section titles for each category.
• When a section is touched, expand it if it is not already expanded. Otherwise, collapse the section.
• When a section is touched, expand it and if another section is currently expanded collapse that section so that only one section is expanded at a time.
• To expand a section, determine the number of items that must be displayed within that section and insert that number of rows in the UITableView; then display the items in the newly inserted rows.
• To collapse a section, determine the number of items currently displayed within that section and delete that number of rows from the UITableView.

To reload one section only : 

[self.tableView beginUpdates];
 (void)reloadSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation:
[self.tableView endUpdates];