xcode 是否可以使用 popViewControllerAnimated 传递数据？

it possible to Pass Data with popViewControllerAnimated?

提问by Sosily

I came across an interesting problem, i have main ViewController let's call him MainVC with navigationController and i am doing performSegueWithIdentifier from him to Mine second ViewController let's call him SecVC. so when i am trying to do the popViewControllerAnimated i want to pass some data from the SecVC to the MainVc.. i know i can do it with appDelegate Param or with singletons class but my question is : can i do it with more Elegant solution? like i use prepareForSegue and use local parmeters..

我遇到了一个有趣的问题，我有主 ViewController，让我们用导航控制器称他为 MainVC，我正在执行从他到我的第二个 ViewController 的 performSegueWithIdentifier，让我们称他为 SecVC。因此，当我尝试执行 popViewControllerAnimated 时，我想将一些数据从 SecVC 传递到 MainVc。就像我使用 prepareForSegue 并使用本地参数一样..

Thank you...

谢谢...

回答by Saliom

The best way to do it is by using a delegate.

最好的方法是使用委托。

//SecVCDelegate.h

//SecVCDelegate.h

#import <Foundation/Foundation.h>

@protocol SecVSDelegate <NSObject>

@optional
- (void)secVCDidDismisWithData:(NSObject*)data;
@end

//SecVC.h

//SecVC.h

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

@interface SecVC : UIViewController

/** Returns the delegate */
@property (nonatomic, assign)   id<SecVSDelegate> delegate;

@end

//SecVC.M

//SecVC.M

...

- (void) dealloc
{
...
delegate = nil
...
}

When ever you popViewControllerAnimated, right after it (or before it) you do this

当你 popViewControllerAnimated 时，就在它之后（或之前）你这样做

if(_delegate && [_delegate respondsToSelector:@selector(secVCDidDismisWithData:)])
{
[_delegate secVCDidDismisWithData:myDataObject];
}

And in the MainVC you must be certain that you implement the delegate function //MainVC.m

在 MainVC 中，您必须确定您实现了委托函数 //MainVC.m

- (void)secVCDidDismisWithData
{
//do whatever you want with the data
}

To avoid any warnings you must tell that the MainVC class implements the delegate like this:

为了避免任何警告，您必须告诉 MainVC 类实现了这样的委托：

//MainVC.h

//主VC.h

#import "SecVCDelegate.h"
...
@interface MainVC : UIViewController <SecVCDelegate>
...
secVCInstance.delegate = self;
[self.navigationController pushViewController:secVCInstance]; 
...

回答by Atif Alvi

While I agree that the best option is to use Delegate, but still if any one is looking for something different, he can use NSNotificationCenteras an alternative.

虽然我同意最好的选择是使用Delegate，但如果有人正在寻找不同的东西，他可以使用NSNotificationCenter作为替代。

In viewDidLoadof MainVC:

在MainVC 的viewDidLoad中：

- (void)viewDidLoad
{

    [super viewDidLoad];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(recvData:)
                                             name:@"SecVCPopped"
                                           object:nil];
}

And add method recvDatain MainVC.m

相加法recvData在MainVC.m

- (void) recvData:(NSNotification *) notification
{

    NSDictionary* userInfo = notification.userInfo;
    int messageTotal = [[userInfo objectForKey:@"total"] intValue];
    NSLog (@"Successfully received data from notification! %i", messageTotal);
}

Now in SecVC, before popping, add this line

现在在 SecVC 中，在弹出之前，添加这一行

NSMutableDictionary* userInfo = [NSMutableDictionary dictionary];
[userInfo setObject:[NSNumber numberWithInt:messageTotal] forKey:@"total"];

NSNotificationCenter* nc = [NSNotificationCenter defaultCenter];
[nc postNotificationName:@"SecVCPopped" object:self userInfo:userInfo];

回答by John

I would do it in one of the following ways, but I'm not sure if it's elegant enough...

我会通过以下方式之一来做，但我不确定它是否足够优雅......

1. In SecVC, add an @property MainVC *mainVC;Use [self.mainVC setSomeValue:...];before calling [self.navigationController popViewControllerAnimated:...];

2. Use [self.navigationController viewControllers]; to find out the MainVC *mainVC, and call [mainVC setSomeValue:...];before the line of code that pop the ViewController.

1. 在SecVC中，调用前加一个@property MainVC *mainVC;Use[self.mainVC setSomeValue:...];[self.navigationController popViewControllerAnimated:...];

2. 使用 [self.navigationController viewControllers]; 找出MainVC *mainVC, 并[mainVC setSomeValue:...];在弹出ViewController.

Is this what you want?

这是你想要的吗？

回答by Harry Bloom

I simply set up a protocol in the view being dismissed (example in Swift):

我只是在被驳回的视图中设置了一个协议（Swift 中的示例）：

 protocol ExampleTableViewControllerDismissDelegate {
    func didDismiss(withData: Any)
}

var delegate: SearchableTableViewControllerDismissDelegate?

You can then call this when you dismiss/pop your view like this

然后，当您像这样关闭/弹出您的视图时，您可以调用它

self.navigationController?.popViewController(animated: true)
delegate?.didDismiss(withData: Any)

Then in the view being dismissed to (the parent in the hierarchy), we can conform to the delegate and essentially get a callback with the data after the view has been dismissed.

然后在视图被解散到（层次结构中的父级）中，我们可以符合委托并在视图被解散后本质上获得带有数据的回调。

//MARK: ExampleTableViewControllerDismissDelegate

func didDismiss(withData: Any) {
    //do some funky stuff
}

And don't forget to subscribe to the delegate in the parent view by using

并且不要忘记通过使用订阅父视图中的委托

viewController.delegate = self

回答by lojals

There is another way to pass data between views including popViewControllerAnimatedand it's with a global var instance, so If you modify that Var in your detail view and after do the popViewControllerAnimated, you can call the new data in the viewWillAppear method.

还有另一种在视图之间传递数据的方法，包括popViewControllerAnimated并且它使用全局 var 实例，因此如果您在详细视图中修改该 Var 并在执行popViewControllerAnimated 之后，您可以在 viewWillAppear 方法中调用新数据。

The first step is declare the Global var in main.h

第一步是在main.h中声明全局变量

NSMutableArray * layerList;

And now you have to call it in detail view.

现在您必须在详细信息视图中调用它。

SecondView.m

第二视图.m

extern NSString *layerList;

SecondView.h

第二视图.h

-(void)back{
    layerList = @"Value to send";
    [self.navigationController popViewControllerAnimated:YES];
}

Now you can use the information in the Master View after detect the pop action.

现在您可以在检测到弹出操作后使用主视图中的信息。

FirstView.m

FirstView.m

extern NSString *layerList;

FirstView.h

第一视图.h

-(void)viewWillAppear:(BOOL)animated{
   NSLog(@"This is what I received: %@",layerList);
}