135为每行单元格设置展开子项

效果如下：

ViewController.h

#import <UIKit/UIKit.h>
#import "HeaderViewDelegate.h"
#import "HeaderView.h"

@interface ViewController : UITableViewController<HeaderViewDelegate>
@property (strong, nonatomic) NSMutableArray *mArrHeaderView;
@property (assign, nonatomic) NSInteger currentSection;
@property (assign, nonatomic) NSInteger currentRow;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()
- (void)layoutUI;
@end

@implementation ViewController
#define kSectionCount 6
#define kRowCount 8
#define kWidthForHeaderView self.view.frame.size.width
#define kHeightForHeaderView 45
#define kHeightForFooterView 1

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self layoutUI];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)layoutUI {
    _currentSection = -1;
    _currentRow = -1;
    _mArrHeaderView = [[NSMutableArray alloc] initWithCapacity:kSectionCount];
    for (NSInteger i=0; i<kSectionCount; i++) {
        HeaderView *headerView = [[HeaderView alloc] initWithFrame:CGRectMake(0, 0, kWidthForHeaderView, kHeightForHeaderView)];
        headerView.delegate = self;
        [headerView.btnBack setTitle:[NSString stringWithFormat:@"第%ld组", (long)i] forState:UIControlStateNormal];
        headerView.section = i;
        [_mArrHeaderView addObject:headerView];
    }
    self.tableView.separatorInset = UIEdgeInsetsMake(0, 0, 0, 15.0); //设置单元格（上左下右）内边距
    
    self.navigationItem.title = @"为每行单元格设置展开子项";
}

#pragma mark - TableView
//- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
//    return @"列表";
//}

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    return _mArrHeaderView[section];
}

- (UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section {
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, kWidthForHeaderView, kHeightForFooterView)];
    view.backgroundColor = [UIColor grayColor];
    return view;
}

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
    return kHeightForHeaderView;
}

- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
    return kHeightForFooterView;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    HeaderView *headerView = _mArrHeaderView[indexPath.section];
    return headerView.isOpen ? 35.0 : 0;
}

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    HeaderView *headerView = _mArrHeaderView[section];
    return headerView.isOpen ? kRowCount : 0;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *cellIdentifier = @"cellIdentifier";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
    }
    cell.textLabel.text = [NSString stringWithFormat:@"%ld-%ld",(long)indexPath.section,(long)indexPath.row];
    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    _currentSection = indexPath.section;
    _currentRow = indexPath.row;
    [tableView reloadData];
}

#pragma mark - HeaderViewDelegate
- (void)selectedWith:(HeaderView *)view {
    UIImage *img = nil;
    if (view.section == _currentSection) {
        //点击的HeaderView如果是当前已选中的HeaderView时，就进行本身收缩和展开切换
        view.isOpen = !view.isOpen;
        img = [UIImage imageNamed:(view.isOpen ? @"LineIsOpen" : @"LineNormal")];
        [view.btnBack setBackgroundImage:img forState:UIControlStateNormal];
    } else {
        //点击的HeaderView如果不是当前已选中的HeaderView时，就进行先收缩全部的HeaderView，再展开它
        for (HeaderView *headerView in _mArrHeaderView) {
            headerView.isOpen = NO;
            img = [UIImage imageNamed:@"LineNormal"];
            [headerView.btnBack setBackgroundImage:img forState:UIControlStateNormal];
            
        }
        view.isOpen = YES;
        img = [UIImage imageNamed:@"LineIsOpen"];
        [view.btnBack setBackgroundImage:img forState:UIControlStateNormal];
    }
    [self.tableView reloadData];
    
    _currentSection = view.section;
}

@end

HeaderViewDelegate.h

@class HeaderView;

@protocol HeaderViewDelegate <NSObject>
- (void)selectedWith:(HeaderView *)view;

@end

HeaderView.h

#import <UIKit/UIKit.h>
#import "HeaderViewDelegate.h"

@interface HeaderView : UIView
@property (weak, nonatomic) id<HeaderViewDelegate> delegate;
@property (strong, nonatomic) UIButton *btnBack;
@property (assign, nonatomic) NSInteger section;
@property (assign, nonatomic) BOOL isOpen;

@end

HeaderView.m

#import "HeaderView.h"

@implementation HeaderView

- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        _isOpen = NO;
        UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
        btn.frame = frame;
        [btn setBackgroundImage:[UIImage imageNamed:@"LineNormal"]
                       forState:UIControlStateNormal];
        [btn setBackgroundImage:[UIImage imageNamed:@"LineHighlighted"]
                       forState:UIControlStateHighlighted];
        [btn addTarget:self
                action:@selector(execSelected)
      forControlEvents:UIControlEventTouchUpInside];
        [self addSubview:btn];
        _btnBack = btn;
    }
    return self;
}

- (void)execSelected {
    if (_delegate && [_delegate respondsToSelector:@selector(selectedWith:)]) {
        [_delegate selectedWith:self];
    }
}

@end

AppDelegate.h

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) UINavigationController *navigationController;

@end

AppDelegate.m

#import "AppDelegate.h"
#import "ViewController.h"

@interface AppDelegate ()
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    _window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    ViewController *viewController = [[ViewController alloc] init];
    _navigationController = [[UINavigationController alloc] initWithRootViewController:viewController];
    _window.rootViewController = _navigationController;
    //[_window addSubview:_navigationController.view]; //当_window.rootViewController关联时，这一句可有可无
    [_window makeKeyAndVisible];
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application {
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
}

- (void)applicationDidBecomeActive:(UIApplication *)application {
}

- (void)applicationWillTerminate:(UIApplication *)application {
}

@end