这里要达到的效果是A.Nav - push -> B B - push -> C C-pop- >A
以及如果C不popA 则能 C -push - >B B和C相互都能push出来最后他们pop 都能pop 到A 的效果.而且系统自带的手势也能滑到A控制器.

通常情况下，我们的控制器之间的跳转是这样的：

A -present-> B         B -dismiss-> A```
相互之间都是有层级关系和顺序的

首先导航控制器push和pop 是栈先进后出原理
A-push->B B-push->C 之后 控制器的子控制器数组为(A, B, C)
C- pop->A 则要将数组中的B移除, 达到想要的效果

直接上代码
AppDelegate.m中

import "AppDelegate.h"

import "ViewController.h"

import "qqViewController.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];

qqViewController *view = [qqViewController new];
UINavigationController *navi = [[UINavigationController alloc] initWithRootViewController:view];
self.window.rootViewController = navi;
return YES;
}

A控制器qqViewController.m中

import "qqViewController.h"

import "hhViewController.h"

@interface qqViewController ()

@end

@implementation qqViewController

(void)viewDidLoad {
[super viewDidLoad];
self.navigationItem.title = @"首页";
self.view.backgroundColor = [UIColor blackColor];
[self.view addSubview:[self createButton]];
}
(UIButton *)createButton {
UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
button.backgroundColor = [UIColor redColor];
button.frame = CGRectMake(140, 100, 100, 30);
[button setTitle:@"点击" forState:UIControlStateNormal];
[button addTarget:self action:@selector(push) forControlEvents:UIControlEventTouchUpInside];
return button;
}
(void)push {
hhViewController *v = [hhViewController new];
[self.navigationController pushViewController:v animated:YES];
}

B控制器hhViewController.m中

import "hhViewController.h"

import "ccViewController.h"

@interface hhViewController ()
@end

@implementation hhViewController

(void)viewWillAppear:(BOOL)animated {
[self.navigationController setViewControllers:@[self.navigationController.childViewControllers.firstObject, self]];
// 在B控制器将要出现的时候偷梁换柱将导航控制器的ViewControllers中的元素修改掉达到C-pop 回去的是A控制器
}
(void)viewDidLoad {
[super viewDidLoad];
self.navigationItem.title = @"第二";
self.view.backgroundColor = [UIColor redColor];
[self.view addSubview:[self createButton]];
}
(void)push {
ccViewController *v = [ccViewController new];
v.view.backgroundColor = [UIColor grayColor];
[self.navigationController pushViewController:v animated:YES];
}
(UIButton *)createButton {
UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
button.backgroundColor = [UIColor greenColor];
button.frame = CGRectMake(140, 200, 100, 30);
[button setTitle:@"点击" forState:UIControlStateNormal];
[button addTarget:self action:@selector(push) forControlEvents:UIControlEventTouchUpInside];
return button;
}

C控制器ccViewController.m中

import "ccViewController.h"

import "hhViewController.h"

@interface ccViewController ()

@end

@implementation ccViewController

(void)viewWillAppear:(BOOL)animated {
[self.navigationController setViewControllers:@[self.navigationController.childViewControllers.firstObject, self]];
// 在C控制器将要出现的时候偷梁换柱将导航控制器的ViewControllers中的元素修改掉达到C-push->B B-pop->A
}
(void)viewDidLoad {
[super viewDidLoad];
self.navigationItem.title = @"第三";
[self.view addSubview:[self createButton]];
}
(void)push {
hhViewController *v = [hhViewController new];
v.view.backgroundColor = [UIColor redColor];
[self.navigationController pushViewController:v animated:YES];
}
(UIButton *)createButton {
UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
button.backgroundColor = [UIColor greenColor];
button.frame = CGRectMake(100, 200, 100, 30);
[button setTitle:@"点击" forState:UIControlStateNormal];
[button addTarget:self action:@selector(push) forControlEvents:UIControlEventTouchUpInside];
return button;
}


看看运行效果吧


![qh_1.gif](http://upload-images.jianshu.io/upload_images/1788484-a951085ecd4413ea.gif?imageMogr2/auto-orient/strip)


![qh_2.gif](http://upload-images.jianshu.io/upload_images/1788484-4fc594dfdbff77ff.gif?imageMogr2/auto-orient/strip)

以下可以选择性适当忽略:
禁止pop后，**< Back**中的**<**会置灰，文字**Back**却不会(可能又是Apple Inc.的小Bug)。解决方法很简单：在vc中调用以下两句代码。

[self.navigationController setNavigationBarHidden:YES animated:YES];
[self.navigationController setNavigationBarHidden:NO animated:YES];


比如，用户点击backBarButtonItem
时，我提示用户是否继续离开，如果用户选择**OK**则**POP**离开，如果用户选择**NO**则留在本页并执行上面两句，使**<Back**中的**<**恢复正常颜色。

好了。看效果系统导航自带的back在push到C控制器时 back上的第二变成首页 效果还在上面 要怎么消除这个小bug呢，就要看下面的代码啦

因为大部分的App都会给导航设置标题,所以也就要自定义leftBarButtonItem了、但是 大家都知道自定义NavigationBar会使系统自带滑UIScreenEdgePanGestureRecognizer这个手势失效.要怎么修改，看下面的代码把

首先 我们自定义一个导航控制器继承UINavigationController 
在NavigationController.m中代码如下

import "NavigationController.h"

@interface NavigationController ()<UIGestureRecognizerDelegate>

@end

@implementation NavigationController

(void)viewDidLoad {
[super viewDidLoad];

// 如果想把导航系统手势改成全屏滑的时候则是注释的部分
// // 设置代理
// id target = self.interactivePopGestureRecognizer.delegate;
// // 创建手势
// UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:target action:@selector(handleNavigationTransition:)];
// // 设置pan手势的代理
// pan.delegate = self;
// // 添加手势
// [self.view addGestureRecognizer:pan];
// // 将系统自带的手势覆盖掉
// self.interactivePopGestureRecognizer.enabled = NO;

// 在这里我们还是保留系统自带滑动UIScreenEdgePanGestureRecognizer
// 设置代理
self.interactivePopGestureRecognizer.delegate = self;

}
// 表示的意思是:当前控制器是根控制器,那么就不接收触摸事件,只有当不是根控制器时才需要接收事件.

pragma mark - UIGestureRecognizerDelegate

// 是否触发手势

(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
return self.childViewControllers.count > 1;
}

建好之后 回到AppDelegate.m

import "NavigationController.h"

将NavigationController设置成根视图的导航



在B控制器hhViewController.m中
添加自定义item

在viewDidLoad方法中添加
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(pop)];
方法实现

(void)pop {
[self.navigationController popViewControllerAnimated:YES];
}

在C控制器ccViewController.m中
添加自定义item

在viewDidLoad方法中添加
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemStop target:self action:@selector(pop)];
方法实现

(void)pop {
[self.navigationController popViewControllerAnimated:YES];
}

可以看效果啦

![qh_3.gif](http://upload-images.jianshu.io/upload_images/1788484-f54b01514fb4bc02.gif?imageMogr2/auto-orient/strip)


代码如果想简化 直接创建基类继承UIViewController的BaseViewController
将相同的代码都放到里面 在创建A\B\C控制器的时候继承BaseViewController，直接调用父类的方法就行.这里就不演示啦.

附上Demo:https://github.com/catcups/pop

导航之偷梁换柱-pop到指定控制器

导航之偷梁换柱-pop到指定控制器

import "AppDelegate.h"

import "ViewController.h"

import "qqViewController.h"

import "qqViewController.h"

import "hhViewController.h"

import "hhViewController.h"

import "ccViewController.h"

import "ccViewController.h"

import "hhViewController.h"

import "NavigationController.h"

pragma mark - UIGestureRecognizerDelegate

import "NavigationController.h"

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