一、简介

如果2个控制器的view是父子关系(不管是直接还是间接的父子关系)，那么这2个控制器也应该为父子关系。这样不至于控制器死了，它的view还没有销毁。

   
    // 通过addChildViewController添加的控制器都会存在于childViewControllers数组中
    [self addChildViewController:[[XMGOneViewController alloc] init]];
    [self addChildViewController:[[XMGTwoViewController alloc] init]];
    [self addChildViewController:[[XMGThreeViewController alloc] init]];
    
    // 将XMGOneViewController从childViewControllers数组中移除
//    [self.childViewControllers[0] removeFromParentViewController];
}

- (IBAction)buttonClick:(UIButton *)button {
    // 移除其他控制器的view
    [self.showingVc.view removeFromSuperview];
    
    // 获得控制器的位置（索引）
    NSUInteger index = [button.superview.subviews indexOfObject:button];

    // 添加控制器的view
    self.showingVc = self.childViewControllers[index];
    self.showingVc.view.frame = CGRectMake(0, 64, self.view.frame.size.width, self.view.frame.size.height - 64);
    [self.view addSubview:self.showingVc.view];
}

二、带动画效果的

#import "ViewController.h"
#import "XMGOneViewController.h"
#import "XMGTwoViewController.h"
#import "XMGThreeViewController.h"

@interface ViewController ()
/** 正在显示的控制器 */
@property (nonatomic, weak) UIViewController *showingVc;
/** 用来存放子控制器的view */
@property (nonatomic, weak) UIView *contentView;
@end

@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIView *contentView = [[UIView alloc] init];
    contentView.frame = CGRectMake(0, 64, self.view.frame.size.width, self.view.frame.size.height - 64);
    [self.view addSubview:contentView];
    self.contentView = contentView;
    
    [self addChildViewController:[[XMGOneViewController alloc] init]];
//    [self.childViewControllers[0] didMoveToParentViewController:self];
    
    [self addChildViewController:[[XMGTwoViewController alloc] init]];
    [self addChildViewController:[[XMGThreeViewController alloc] init]];
    
    // 当一个控制器从父控制器中移除时。会自动调用控制器的didMoveToParentViewController:方法，并且参数是nil
//    [self.childViewControllers[0] removeFromParentViewController];
}

- (IBAction)buttonClick:(UIButton *)button {
    // 移除其他控制器的view
    [self.showingVc.view removeFromSuperview];
    
    // 获得控制器的位置（索引）
    NSUInteger index = [button.superview.subviews indexOfObject:button];
    
    // 当前控制器的索引
    NSUInteger oldIndex = [self.childViewControllers indexOfObject:self.showingVc];

    // 添加控制器的view
    self.showingVc = self.childViewControllers[index];
    self.showingVc.view.frame = self.contentView.bounds;
    [self.contentView addSubview:self.showingVc.view];
    
    // 动画
    CATransition *animation = [CATransition animation];
    animation.type = @"cube";
    animation.subtype = index > oldIndex ? kCATransitionFromRight : kCATransitionFromLeft;
    animation.duration = 0.5;
    [self.contentView.layer addAnimation:animation forKey:nil];
}

三、回调方法

/**
 * 当前控制器已经被添加到某个父控制器上时就会调用这个方法
 */


- (void)didMoveToParentViewController:(UIViewController *)parent
{
    [super didMoveToParentViewController:parent];
    
    NSLog(@"didMoveToParentViewController - %@", parent);
}

四、级联菜单的两种实现方式

方式一：在一个控制器里实现

#import "ViewController.h"
#import "XMGCategory.h"

@interface ViewController () <UITableViewDataSource, UITableViewDelegate>
/** 右边表格 */
@property (weak, nonatomic) IBOutlet UITableView *subcategoryTableView;
/** 左边表格 */
@property (weak, nonatomic) IBOutlet UITableView *categoryTableView;
/** 所有的类别数据 */
@property (nonatomic, strong) NSArray *categories;
@end

@implementation ViewController

- (NSArray *)categories
{
    if (_categories == nil) {
        NSArray *dictArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"categories" ofType:@"plist"]];
        
        NSMutableArray *categoryArray = [NSMutableArray array];
        for (NSDictionary *dict in dictArray) {
            [categoryArray addObject:[XMGCategory categoryWithDict:dict]];
        }
        _categories = categoryArray;
    }
    return _categories;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
     // 不会自动去调整uiscrollView的contentInset属性
    // self.automaticallyAdjustsScrollViewInsets = NO;
  
   // 默认选中左边表格的第0行
    [self.categoryTableView selectRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0] animated:NO scrollPosition:UITableViewScrollPositionTop];
    
    self.subcategoryTableView.contentInset = UIEdgeInsetsMake(64, 0, 0, 0);
}

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

#pragma mark - Table view data source
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // 左边表格
    if (tableView == self.categoryTableView) return self.categories.count;
    
    // 右边表格
    XMGCategory *c = self.categories[self.categoryTableView.indexPathForSelectedRow.row];
    return c.subcategories.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    // 左边表格
    if (tableView == self.categoryTableView) {
        static NSString *ID = @"category";
        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];
        

        XMGCategory *c = self.categories[indexPath.row];
        
        // 设置普通图片
        cell.imageView.image = [UIImage imageNamed:c.icon];
        // 设置高亮图片（cell选中 -> cell.imageView.highlighted = YES -> cell.imageView显示highlightedImage这个图片）
        cell.imageView.highlightedImage = [UIImage imageNamed:c.highlighted_icon];
        
        // 设置label高亮时的文字颜色
        cell.textLabel.highlightedTextColor = [UIColor redColor];
        
        cell.textLabel.text = c.name;
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;

        
        return cell;
    } else {
        // 右边表格
        static NSString *ID = @"subcategory";
        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];
        
        // 获得左边表格被选中的模型
        XMGCategory *c = self.categories[self.categoryTableView.indexPathForSelectedRow.row];
        cell.textLabel.text = c.subcategories[indexPath.row];
        
        return cell;
    }
}

#pragma mark - <UITableViewDelegate>
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (tableView == self.categoryTableView) {
        [self.subcategoryTableView reloadData];
    }
}

@end

方式二：用父子控制器
1.父控制器

#import "ViewController.h"
#import "XMGCategoryViewController.h"
#import "XMGSubcategoryViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    CGFloat width = self.view.frame.size.width * 0.5;
    CGFloat height = self.view.frame.size.height;
    
    XMGSubcategoryViewController *subcategoryVc = [[XMGSubcategoryViewController alloc] init];
    subcategoryVc.view.frame = CGRectMake(width, 0, width, height);
    [self addChildViewController:subcategoryVc];
    [self.view addSubview:subcategoryVc.view];
    
    XMGCategoryViewController *categoryVc = [[XMGCategoryViewController alloc] init];
    categoryVc.delegate = subcategoryVc;
    categoryVc.view.frame = CGRectMake(0, 0, width, height);
    [self addChildViewController:categoryVc];
    [self.view addSubview:categoryVc.view];
}

@end

2.子控制器一

#import <UIKit/UIKit.h>

@class XMGCategoryViewController;

@protocol XMGCategoryViewControllerDelegate <NSObject>
@optional
- (void)categoryViewController:(XMGCategoryViewController *)categoryViewController didSelectSubcategories:(NSArray *)subcategories;
@end

@interface XMGCategoryViewController : UITableViewController
@property (nonatomic, weak) id<XMGCategoryViewControllerDelegate> delegate;
@end


#import "XMGCategoryViewController.h"
#import "XMGCategory.h"

@interface XMGCategoryViewController ()
/** 所有的类别数据 */
@property (nonatomic, strong) NSArray *categories;
@end

@implementation XMGCategoryViewController

- (NSArray *)categories
{
    if (_categories == nil) {
        NSArray *dictArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"categories" ofType:@"plist"]];
        
        NSMutableArray *categoryArray = [NSMutableArray array];
        for (NSDictionary *dict in dictArray) {
            [categoryArray addObject:[XMGCategory categoryWithDict:dict]];
        }
        _categories = categoryArray;
    }
    return _categories;
}

static NSString *categoryID = @"category";
- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:categoryID];
}

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

#pragma mark - Table view data source
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return self.categories.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:categoryID];
    
    XMGCategory *c = self.categories[indexPath.row];
    
    // 设置普通图片
    cell.imageView.image = [UIImage imageNamed:c.icon];
    // 设置高亮图片（cell选中 -> cell.imageView.highlighted = YES -> cell.imageView显示highlightedImage这个图片）
    cell.imageView.highlightedImage = [UIImage imageNamed:c.highlighted_icon];
    
    // 设置label高亮时的文字颜色
    cell.textLabel.highlightedTextColor = [UIColor redColor];
    
    cell.textLabel.text = c.name;
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    
    return cell;
}

#pragma mark - <代理方法>
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // 告诉代理
    if ([self.delegate respondsToSelector:@selector(categoryViewController:didSelectSubcategories:)]) {
        XMGCategory *c = self.categories[indexPath.row];
        [self.delegate categoryViewController:self didSelectSubcategories:c.subcategories];
    }
}

// 当一个cell被选中的时候，cell内部的子控件都会达到highlighted状态
@end

3.子控制器2

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

@interface XMGSubcategoryViewController : UITableViewController
                        <XMGCategoryViewControllerDelegate>

@end


#import "XMGSubcategoryViewController.h"

@interface XMGSubcategoryViewController ()
/** 子类别数据 */
@property (nonatomic, strong) NSArray *subcategories;
@end

@implementation XMGSubcategoryViewController

static NSString *subcategoryID = @"subcategory";
- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:subcategoryID];
}

#pragma mark - <XMGCategoryViewControllerDelegate>
- (void)categoryViewController:(XMGCategoryViewController *)categoryViewController didSelectSubcategories:(NSArray *)subcategories
{
    self.subcategories = subcategories;
    
    [self.tableView reloadData];
}

#pragma mark - Table view data source
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return self.subcategories.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:subcategoryID];
    cell.textLabel.text = self.subcategories[indexPath.row];
    return cell;
}
@end