ios - 带有委托(delegate)的 objective-c 文本字段不起作用

Question

我正在学习 objective-c ，需要帮助来理解委托(delegate)。

我在 FirstViewController 中有一个 UITextField，我想显示在 SecondViewController 中输入的文本。

但它不起作用。我究竟做错了什么？

这是我的代码:

第一 View Controller .h

#import <UIKit/UIKit.h>

@interface FirstViewController : UIViewController 

@property (weak, nonatomic) IBOutlet UIButton *accessButton;
@property (weak, nonatomic) IBOutlet UITextField *codeField;
@property (nonatomic, retain) NSString *getCodeString;

@end

SecondViewController.h

#import <UIKit/UIKit.h>

@class CodeField;

@protocol CodeFieldHandlerDelegate <NSObject>

@property NSString *saveCodeString;

@end

@interface SecondViewController : UIViewController

@property (weak, nonatomic) IBOutlet UILabel *candidateLabel;

@property (weak, nonatomic) id <CodeFieldHandlerDelegate> myDelegate;

@end

第一 View Controller .m

#import "FirstViewController.h"
#import "SecondViewController.h"

@interface FirstViewController ()

<CodeFieldHandlerDelegate>

@property (nonatomic, strong) SecondViewController *secondViewController;

@end

@implementation FirstViewController

@synthesize getCodeString;
@synthesize secondViewController;
@synthesize saveCodeString;

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

- (IBAction)accessButton:(UIButton *)sender {

    //get the input data from text field and store into string
    getCodeString = self.codeField.text;

    //go keypad back when button clicked from textfield
    [self.codeField resignFirstResponder];

    secondViewController = [[SecondViewController alloc] init]; 
    secondViewController.myDelegate = self;

    [self.navigationController pushViewController:secondViewController animated:YES];

}

// name of this string is the same of the NSString in the delegate
- (NSString *) saveCodeString {
    return getCodeString;
}

@end

和 SecondViewController.m

 #import "SecondViewController.h"

 @interface SecondViewController ()

 @end

 @implementation SecondViewController

 @synthesize candidateLabel;
 @synthesize myDelegate;

 - (void)viewDidLoad {
    [super viewDidLoad];

     self.candidateLabel.text = [myDelegate saveCodeString];
}

@end

Answer 1

我相信您正在对 SecondViewController 进行转场。错误的方法。你有没有得到 FirstViewController 的转场？到SecondViewController在职的？

试试这个:

secondViewController = (SecondViewController *)[[UIStoryboard storyboardWithName:@"YOUR STORYBOARD NAME" bundle:nil] instantiateViewControllerWithIdentifier:@"YOUR CONTROLLER IDENTIFIER"];