How to expand and collapse rows using header section in a UITableView

Question

I have a table view. Now I want to collapse and expand rows by tapping on the section header. In other words, when I tap the header the rows display for that section. How ca

Answer 1

TLIndexPathTools does this with only a few lines of code on your part. Try running the Collapse sample project. It subclasses TLCollapsibleTableViewController, which has a couple of nice options. It supports expanding a single section at a time or multiple sections. It also optimizes the scroll position when you expand a section to show as many rows of the section as possible. So if you tap on a section near the bottom of the screen, it will scroll up automatically.

The full view controller code of the sample project is as follows:

#import "TLCollapsibleTableViewController.h"

@interface CollapseTableViewController : TLCollapsibleTableViewController
- (IBAction)toggleSingleSectionExpanded:(UISwitch *)sender;
@end

#import "CollapseTableViewController.h"
#import "TLIndexPathSectionInfo.h"
#import "TLCollapsibleDataModel.h"

#define SECTION1_NAME @"Section 1"
#define SECTION2_NAME @"Section 2"

@interface CollapseTableViewController ()
@property (strong, nonatomic) TLIndexPathDataModel *backingDataModel;
@end

@implementation CollapseTableViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    //define items for two sections
    NSArray *section1Items = @[
                               @"Fredricksburg",
                               @"George Washington",
                               @"Grand Canyon"];
    NSArray *section2Items = @[
                               @"Jelly Bean",
                               @"Bibliography",
                               @"Keyboard Shortcut",
                               @"Metadata",
                               @"Fundamental",
                               @"Cellar Door"];

    //We're using plain string items, so we don't have a sectionNameKeyPath property
    //to use, so instead we explicitly create section info objects
    TLIndexPathSectionInfo *section1 = [[TLIndexPathSectionInfo alloc] initWithItems:section1Items andName:SECTION1_NAME];
    TLIndexPathSectionInfo *section2 = [[TLIndexPathSectionInfo alloc] initWithItems:section2Items andName:SECTION2_NAME];

    //create the backing model, which contains all sections and items
    self.backingDataModel = [[TLIndexPathDataModel alloc] initWithSectionInfos:@[section1, section2]
                                                                           andIdentifierKeyPath:nil andCellIdentifierKeyPath:nil];

    [self collapseAll];
}

- (void)tableView:(UITableView *)tableView configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
    NSString *item = [self.dataModel itemAtIndexPath:indexPath];
    cell.textLabel.text = item;
}

- (IBAction)toggleSingleSectionExpanded:(UISwitch *)sender {
    self.singleExpandedSection = sender.isOn;
    [self collapseAll];
}

- (void)collapseAll
{
    self.dataModel = [[TLCollapsibleDataModel alloc] initWithBackingDataModel:self.backingDataModel
                                                        collapsedSectionNames:[NSSet setWithArray:self.backingDataModel.sectionNames]];
}

@end