Objective c - 使用委托传回字符串值 [英] Objective c - pass back string value using delegate

问题描述

我想使用委托将GreenViewController中的UITextField * nameText传递给ViewController中的UILabel * nameValue。

I want to pass UITextField *nameText from GreenViewController to UILabel *nameValue in ViewController using delegate.

我创建了委托，调用了ViewController中的onSave方法但是屏幕不回去，名字没有通过。
有什么问题？
以下是标题和紧急文件：

I made delegate, the onSave method in ViewController is called but the screen is not going back and the name is not passed. What is the problem? Here are the header and impelentation files:

GreenViewController.h

GreenViewController.h

#import <UIKit/UIKit.h>

@protocol GreenViewDelegate <NSObject>
-(void)onSave:(NSString*)nameValue;

@end


@interface GreenViewController : UIViewController

@property id<GreenViewDelegate> delegate;
@property (nonatomic) NSString* sliderValuePassed;
@property (weak, nonatomic) IBOutlet UIButton *Next;
@property (weak, nonatomic) IBOutlet UIButton *Save;
@property (weak, nonatomic) IBOutlet UIButton *Back;
@property (weak, nonatomic) IBOutlet UILabel *sliderTextValue;
@property (weak, nonatomic) IBOutlet UITextField *NameText;

- (IBAction)save:(id)sender;

@end

GreenViewController.m

GreenViewController.m

#import "GreenViewController.h"
#import "ViewController.h"

@interface GreenViewController ()

@end

@implementation GreenViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.sliderTextValue.text = self.sliderValuePassed;
}
- (IBAction)back:(id)sender {
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (IBAction)save:(id)sender {
    [self.delegate onSave:self.NameText.text];
    [self.navigationController popViewControllerAnimated:YES];
}

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

@end

ViewController.h

ViewController.h

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

@interface ViewController : UIViewController <GreenViewDelegate>
@property (weak, nonatomic) IBOutlet UISlider *slider;
@property (weak, nonatomic) IBOutlet UILabel *sliderTextValue;
@property (weak, nonatomic) IBOutlet UIButton *EnterName;
@property (weak, nonatomic) IBOutlet UILabel *NameValue;
@property (weak, nonatomic) IBOutlet UIButton *LikeIOS;
@property (weak, nonatomic) IBOutlet UISwitch *CheckboxIOS;

@end

ViewController.m

ViewController.m

#import "ViewController.h"
#import "RedViewController.h"
#import "GreenViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.sliderTextValue.text = [NSString stringWithFormat:@"Slider value = %d",(int)self.slider.value];
}


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

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

    if ([segue.identifier isEqualToString:@"yellowToGreen"]){
        GreenViewController* gVC = segue.destinationViewController;
        gVC.sliderValuePassed = [NSString stringWithFormat:@"Slider value = %d",(int)self.slider.value];
        gVC.delegate = self;
    }else if([segue.identifier isEqualToString:@"yellowToRed"]){
        RedViewController* rVC = segue.destinationViewController;
        rVC.sliderValuePassed = [NSString stringWithFormat:@"Slider value = %d",(int)self.slider.value];
        rVC.CheckboxIOS = self.CheckboxIOS;
    }
}

- (IBAction)sliderChangeValue:(id)sender {
    int sliderVal = self.slider.value;
    self.sliderTextValue.text = [NSString stringWithFormat:@"Slider value = %d",sliderVal];
}

-(void)onSave:(NSString*)nameValue{
    NSLog(@"onSave in father controller");
    self.NameValue.text = [NSString stringWithFormat:@"Name = %@",nameValue];
}

@end

推荐答案

我假设您没有设置代理。

I assume you didnt set the delegate .

设置如下：

  GreenViewController *myVc = [[GreenViewController alloc] init];

  myVc.delegate = self;

把它放在你的视图控制器视图中加载方法!!!

Put this in your view controller view did load method!!!

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