在另一个视图控制器中更改标签的文本 [英] Changing label's text in another view controller

问题描述

我有一个名为 FirstViewController 的视图控制器和一个名为 SecondViewController 的视图控制器.我用

I have one view controller named FirstViewController, and a second named SecondViewController. I present second view controller with

 UIViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:@"mainController"];
[self presentViewController:controller animated:YES completion:nil];

在 SecondViewController 的 .m 中，我想更改 FirstViewController 中 UILabel 的文本.但是，标签的文本不会更新.我如何才能在 SecondViewController 中按下 UIButton 时更新 FirstViewController 的标签?

In SecondViewController's .m, I want to change the text of a UILabel in FirstViewController. However, the label's text isn't updating. How would I make it so that the FirstViewController's label is updated when a UIButton is pressed in SecondViewController?

推荐答案

你可以使用委托模式

首先创建您的委托协议

@class SecondViewController;

@protocol SecondViewControllerDelegate

-(void) updateLabelWithString:(NSString*)string

@end

@property (weak, nonatomic) id<SecondViewControllerDelegate>delegate;

在你的 IBAction 连接到你的 UIButton

In your IBAction connected to your UIButton

[self.delegate updateLabelWithString:yourString];

在 FirstViewController.h 中

in FirstViewController.h

#import "SecondViewController.h"

@interface FirstViewController : UIViewController <SecondViewControllerDelegate>

在 FirstViewController.m 中

in FirstViewController.m

-(void) updateLabelWithString:(NSString*)string {
   label.text = string;
} 

然后在创建控制器实例时，将 FirstViewController 设置为 mainViewController 的委托

then when you create your controller instance, set FirstViewController as the delegate for your mainViewController

controller.delegate = self;

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