Expand/collapse section in UITableView in iOS

Question

Could somebody tell me the way to perform UITableView expandable/collapsible animations in sections of UITableView as below?

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Answer 1

I've used a NSDictionary as datasource, this looks like a lot of code, but it's really simple and works very well! how looks here

I created a enum for the sections

typedef NS_ENUM(NSUInteger, TableViewSection) {

    TableViewSection0 = 0,
    TableViewSection1,
    TableViewSection2,
    TableViewSectionCount
};

sections property:

@property (nonatomic, strong) NSMutableDictionary * sectionsDisctionary;

A method returning my sections:

-(NSArray  * )sections{

    return @[@(TableViewSection0), @(TableViewSection1), @(TableViewSection2)];
}

And then setup my data soruce:

-(void)loadAndSetupData{

    self.sectionsDisctionary = [NSMutableDictionary dictionary];

    NSArray * sections = [self sections];

    for (NSNumber * section in sections) {

    NSArray * sectionObjects = [self objectsForSection:section.integerValue];

    [self.sectionsDisctionary setObject:[NSMutableDictionary dictionaryWithDictionary:@{@"visible" : @YES, @"objects" : sectionObjects}] forKey:section];
    }
}

-(NSArray *)objectsForSection:(NSInteger)section{

    NSArray * objects;

    switch (section) {

        case TableViewSection0:

            objects = @[] // objects for section 0;
            break;

        case TableViewSection1:

            objects = @[] // objects for section 1;
            break;

        case TableViewSection2:

            objects = @[] // objects for section 2;
            break;

        default:
            break;
    }

    return objects;
}

The next methods, will help you to know when a section is opened, and how to respond to tableview datasource:

Respond the section to datasource:

/**
 *  Asks the delegate for a view object to display in the header of the specified section of the table view.
 *
 *  @param tableView The table-view object asking for the view object.
 *  @param section   An index number identifying a section of tableView .
 *
 *  @return A view object to be displayed in the header of section .
 */
- (UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section{

    NSString * headerName = [self titleForSection:section];

    YourCustomSectionHeaderClass * header = (YourCustomSectionHeaderClass *)[tableView dequeueReusableHeaderFooterViewWithIdentifier:YourCustomSectionHeaderClassIdentifier];

    [header setTag:section];
    [header addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapGesture:)]];
    header.title = headerName;
    header.collapsed = [self sectionIsOpened:section];


    return header;
}

/**
 * Asks the data source to return the number of sections in the table view
 *
 * @param An object representing the table view requesting this information.
 * @return The number of sections in tableView.
 */
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
    // Return the number of sections.

    return self.sectionsDisctionary.count;
}

/**
 * Tells the data source to return the number of rows in a given section of a table view
 *
 * @param tableView: The table-view object requesting this information.
 * @param section: An index number identifying a section in tableView.
 * @return The number of rows in section.
 */
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{

    BOOL sectionOpened = [self sectionIsOpened:section];
    return sectionOpened ? [[self objectsForSection:section] count] : 0;
}

Tools:

/**
 Return the section at the given index

 @param index the index

 @return The section in the given index
 */
-(NSMutableDictionary *)sectionAtIndex:(NSInteger)index{

    NSString * asectionKey = [self.sectionsDisctionary.allKeys objectAtIndex:index];

    return [self.sectionsDisctionary objectForKey:asectionKey];
}

/**
 Check if a section is currently opened

 @param section the section to check

 @return YES if is opened
 */
-(BOOL)sectionIsOpened:(NSInteger)section{

    NSDictionary * asection = [self sectionAtIndex:section];
    BOOL sectionOpened = [[asection objectForKey:@"visible"] boolValue];

    return sectionOpened;
}


/**
 Handle the section tap

 @param tap the UITapGestureRecognizer
 */
- (void)handleTapGesture:(UITapGestureRecognizer*)tap{

    NSInteger index = tap.view.tag;

    [self toggleSection:index];
}

Toggle section visibility

/**
 Switch the state of the section at the given section number

 @param section the section number
 */
-(void)toggleSection:(NSInteger)section{

    if (index >= 0){

        NSMutableDictionary * asection = [self sectionAtIndex:section];

        [asection setObject:@(![self sectionIsOpened:section]) forKey:@"visible"];

        [self.tableView reloadSections:[NSIndexSet indexSetWithIndex:section] withRowAnimation:UITableViewRowAnimationFade];
    }
}