在多个视图控制器中使用代理 [英] Using Delegates in multiple view controllers

问题描述

我正在使用多个视图控制器，并使用委托将一个视图控制器中的UITextfield链接到另一个视图控制器中的标签。

ViewController.h

  #import< UIKit / UIKit.h> 
 
 @interface ViewController：UIViewController< UITextFieldDelegate> 
 {
 IBOutlet UITextField * txtField; 
 
} 
 
 @end 
  

ViewController。 m

  #importViewController.h
 #importViewController2nd.h
 
 
 @interface ViewController（）
 
 @end 
 
 @implementation ViewController 
 
  - （void）viewDidLoad 
 {
 [super viewDidLoad]; 
 //加载视图后，通常从笔尖进行任何其他设置。 
} 
 
  - （void）didReceiveMemoryWarning 
 {
 [super didReceiveMemoryWarning]; 
 //处理可以重新创建的任何资源。 
} 
  - （BOOL）textFieldShouldReturn :( UITextField *）textField {
 
 lbl.text = [NSString stringWithFormat：@Hello，％@，txtField.text] 
 [txtField resignFirstResponder]; 
返回YES; 
} 
 
 @end 
  

ViewController2nd.h

  #import< UIKit / UIKit.h> 
 
 @interface ViewController2nd：UIViewController< UITextFieldDelegate> {
 
 IBOutlet UILabel * lbl; 
} 
 
 @end 
  

ViewController2nd.m

  #importViewController2nd.h
 
 @interface ViewController2nd（）
 
 @ end 
 
 @implementation ViewController2nd 
 
  - （id）initWithNibName：（NSString *）nibNameOrNil bundle：（NSBundle *）nibBundleOrNil 
 {
 self = super initWithNibName：nibNameOrNil bundle：nibBundleOrNil]; 
 if（self）{
 //自定义初始化
} 
 return self; 
} 
 
  - （void）viewDidLoad 
 {
 [super viewDidLoad]; 
 //从其笔尖加载视图后，请执行任何其他设置。 
} 
 
  - （void）didReceiveMemoryWarning 
 {
 [super didReceiveMemoryWarning]; 
 //处理可以重新创建的任何资源。 
} 
 
 @end 
  

我得到的错误是：

在Viewcontroller.m中使用未声明的标识符lbl

不知道如何解决这个问题。需要一些指导..谢谢...

解决方案

您没有范围/超出 ViewController2nd 的 IBOutlet UILabel * lbl; 在 ViewController 中，您需要自定义代理 ViewController 代理 ViewController2nd 并传回数据。有关详细信息，请查看此帖。

I am using multiple view controllers and trying the link the UITextfield in one view controller to the label in another view controller using delegate.

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UITextFieldDelegate>
{
    IBOutlet UITextField *txtField;

}

@end

ViewController.m

#import "ViewController.h"
#import "ViewController2nd.h"


@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField{

    lbl.text = [NSString stringWithFormat:@"Hello, %@",txtField.text]
    [txtField resignFirstResponder];
    return YES;
}

@end

ViewController2nd.h

#import <UIKit/UIKit.h>

@interface ViewController2nd : UIViewController <UITextFieldDelegate> {

    IBOutlet UILabel *lbl;
}

@end

ViewController2nd.m

#import "ViewController2nd.h"

@interface ViewController2nd ()

@end

@implementation ViewController2nd

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

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

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

@end

The error i get is:

Use of undeclared identifier lbl in Viewcontroller.m

Not sure how to solve this problem. Need some guidance.. Thanks...

解决方案

You don't have scope/excess of ViewController2nd's IBOutlet UILabel *lbl; in ViewController for this you need custom delegates, a ViewController a delegate of ViewController2nd and pass data back. Have a look at this post for more details.

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