将数据传回前一个视图控制器 [英] Pass data back to previous viewcontroller

问题描述

我正在尝试将数据传递回之前的 viewController.

I am trying to pass data BACK TO previous viewController.

有谁知道如何将数据从 ViewController B 传递回 ViewController A?所以我想要一个字符串从"BIDAddTypeOfDealViewController 到 BIDDCCreateViewController.用户编辑 viewController B，我希望将编辑后的数据返回到 ViewController A 中，然后在其中使用它.

Does anyone know how to pass data back from ViewController B to ViewController A? So I want a string to go 'from' BIDAddTypeOfDealViewController to BIDDCCreateViewController. A user edits viewController B and I want that edited data back in ViewController A where I then use it.

我正在使用 this answer 的传回数据"部分.我的不同之处:第 3 点和第 6 点只提到了何时弹出视图，所以我将该代码放在 viewWillDisappear 中.我认为这是正确的?同样在第 6 点上，我没有使用 nib 进行初始化，因为它是旧的.我正在使用故事板.我没有添加最后一行，因为我不相信我必须推动它.在我的故事板上按下一个按钮已经让我前进了.

I am using the 'passing data back' section of this answer. How mine differs: Point 3 and 6 just mentions when views are popped so I have put that code in viewWillDisappear. I think that is correct? Also on Point 6 I did not initialise with nib as that is old. I'm using storyboards. And I did not add that last line as I do not believe I would have to push it. Pressing a button on my storyboard already takes me forward.

我认为问题可能出现在 BIDDCCreateViewController 中，我有方法但无法运行.要运行一个方法，它应该去 [self 方法].我无法做到这一点.嗯，这正是我的猜测.

I think the problem may arise in BIDDCCreateViewController, I have the method but I cannot run it. To run a method it should go [self method]. I am unable to do that. Well that is just what I am guessing.

它编译并运行良好，只是没有记录任何内容，所以我不知道它是否有效.

It compiles and runs fine just nothing is logged, so I don't know if it works.

更新:我无法执行sendDataToA"方法.

UPDATE: I am unable to get the 'sendDataToA' method to execute.

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

 @interface BIDDCCreateViewController : UIViewController
 @property (strong, nonatomic) NSString *placeId;
- (IBAction)gotoBViewController:(id)sender;
@end


#import "BIDDCCreateViewController.h"
#import "BIDAddTypeOfDealViewController.h"

@implementation BIDDCCreateViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    NSLog(@"SUCCESSFULLY PASSED PLACE ID: %@", self.placeId);
}

-(void)sendDataToA:(NSString *)myStringData
{

    NSLog(@"Inside sendDataToA");
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Your string Data Showing" message:myStringData delegate:self cancelButtonTitle:@"Ok " otherButtonTitles:nil];
    [alert show];
}

- (IBAction)gotoBViewController:(id)sender {
    NSLog(@"pressed");
    BIDAddTypeOfDealViewController *bidAddType = [[BIDAddTypeOfDealViewController alloc]init];
    bidAddType.delegate = self;

}
@end


@protocol senddataProtocol <NSObject>
-(void)sendDataToA:(NSString *)myStringData;
@end

#import <UIKit/UIKit.h>
@interface BIDAddTypeOfDealViewController : UIViewController <UITextFieldDelegate>//Using this delegate for data a user inputs
@property(nonatomic,assign)id delegate;
//other textfield outlets not relevant
- (IBAction)chooseDiscountDeal:(id)sender;
@end

#import "BIDAddTypeOfDealViewController.h"

@interface BIDAddTypeOfDealViewController ()

@end

@implementation BIDAddTypeOfDealViewController
@synthesize delegate;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

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

-(void)viewWillDisappear:(BOOL)animated
{
    [delegate sendDataToA:@"Apple"];
}
@end

推荐答案

您可以使用委托.因此，在您的 ViewController B 中，您需要创建一个将数据发送回 ViewController A 的协议.您的 ViewController A 将成为 ViewController B 的代表.

You can use a delegate. So in your ViewController B you need to create a protocol that sends data back to your ViewController A. Your ViewController A would become a delegate of ViewController B.

如果您不熟悉目标 C，请查看什么是委托.

If you are new to objective C, please look at What is Delegate.

在 ViewControllerB.h 中创建协议:

Create protocol in ViewControllerB.h :

#import <UIKit/UIKit.h>

@protocol senddataProtocol <NSObject>

-(void)sendDataToA:(NSArray *)array; //I am thinking my data is NSArray, you can use another object for store your information. 

@end

@interface ViewControllerB : UIViewController

@property(nonatomic,assign)id delegate;

ViewControllerB.m

ViewControllerB.m

@synthesize delegate;
-(void)viewWillDisappear:(BOOL)animated
{
     [delegate sendDataToA:yourdata];

}

在您的 ViewControllerA 中:当您转到 ViewControllerB 时

in your ViewControllerA : when you go to ViewControllerB

ViewControllerA *acontollerobject=[[ViewControllerA alloc] initWithNibName:@"ViewControllerA" bundle:nil];
acontollerobject.delegate=self; // protocol listener
[self.navigationController pushViewController:acontollerobject animated:YES];

并定义你的功能:

-(void)sendDataToA:(NSArray *)array
{
   // data will come here inside of ViewControllerA
}

已

您可以查看此示例:如何将数据传递回以前的视图控制器:教程链接

You can See this example : How you can Pass data back to previous viewcontroller: Tutorial link

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