如何将值传递给另一个视图控制器？

Question

大家好，我在UIViewController 中有一个UITableView。当点击表格中的一行时，我正在收集单元格的文本值并将其放入一个名为 localstringGValue 的字符串中。

我想传递这个字符串并将其显示在另一个viewController 中，但不使用-pushViewController：我希望将此值存储在NSUserDefaults 或NSDictonary 之类的地方，然后在viewWillapper 上另一个视图控制器我希望这个存储的值显示在标签中。

在我的.h：

 NSString *localStringGValue;

在我的.m:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    [tableView deselectRowAtIndexPath:indexPath animated:YES];

    localStringGValue = [tableView cellForRowAtIndexPath:indexPath].textLabel.text; 
}

在我的另一个视图控制器中：

-(void)viewWillAppear
{
    label.text=localStringGValue;
}

提前致谢。

Answer 1

保存到 nsuserdefaults:

[[NSUserDefaults standardUserDefaults] setObject:localstringGValue forKey:@"localstringGValue"];
[[NSUserDefaults standardUserDefaults] synchronize];

从 nsuserdefaults 中检索：

NString *localstringGValue = [[NSUserDefaults standardUserDefaults] objectForKey:@"localstringGValue"];

Answer 2

只需使用delegate。在推送“UploadViewController”实例之前，您需要将其设置为 delegate 为 self（在 GoogleDocMainPageController.m 中）。每次选择表格单元格时，它会通过调度self.delegate 的方法为self.delegate（这里是GoogleDocMainPageController 实例）设置值，该方法由GoogleDocMainPageController 实现：

[self.delegate setDataAfterSelectedTabelCell:[NSString stringWithFormat:@"TalbeCell %d selected", [indexPath row]]];

主要代码如下：
UploadViewController.h：

#import <UIKit/UIKit.h>

@class UploadViewController;

@protocol UploadViewControllerDelegate <NSObject>

- (void)setDataAfterSelectedTabelCell:(NSString *)stringValueInCell;

@end

@interface UploadViewController : UITableViewController

@property (nonatomic, retain) id <UploadViewControllerDelegate> delegate;

@end

UploadViewController.m：

//...
@synthesize delegate = _delegate;

//...
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [self.delegate setDataAfterSelectedTabelCell:[NSString stringWithFormat:@"TalbeCell %d selected", [indexPath row]]];
}

GoogleDocMainPageController.h：

#import <UIKit/UIKit.h>

#import "UploadViewController.h"

@class UploadViewController;

@interface GoogleDocMainPageController : UIViewController <UploadViewControllerDelegate>

- (void)loadUploadViewController;

@property (nonatomic, retain) UILabel * glLabel;
@property (nonatomic, retain) UploadViewController * uploadViewController;

@end

GoogleDocMainPageController.m：

//...
@synthesize glLabel = _glLabel;
@synthesize uploadViewController = _uploadViewController;

//...
- (void)viewDidLoad
{
    [super viewDidLoad];

    UIButton * uploadButton = [[UIButton alloc] initWithFrame:CGRectMake(10.0f, 160.0f, 300.0f, 35.0f)];
    [uploadButton setBackgroundColor:[UIColor blackColor]];
    [uploadButton setTitle:@"Upload Button" forState:UIControlStateNormal];
    [uploadButton addTarget:self action:@selector(loadUploadViewController) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:uploadButton];
    [uploadButton release];

    self.glLabel = [[UILabel alloc] initWithFrame:CGRectMake(10.0f, 200.0f, 300.0f, 35.0f)];
    [self.glLabel setBackgroundColor:[UIColor blackColor]];
    [self.glLabel setTextColor:[UIColor whiteColor]];
    [self.glLabel setTextAlignment:UITextAlignmentCenter];
    [self.glLabel setText:@"Default"];
    [self.view addSubview:self.glLabel];

    self.uploadViewController = [[UploadViewController alloc] initWithStyle:UITableViewStylePlain];
}

//...
#pragma mark -

- (void)loadUploadViewController
{
    [self.uploadViewController setDelegate:self];
    [self.navigationController pushViewController:self.uploadViewController animated:YES];
}

#pragma mark - UploadViewControllerDelegate

- (void)setDataAfterSelectedTabelCell:(NSString *)stringValueInCell
{
    [self.glLabel setText:stringValueInCell];
}

Answer 3

你为什么不声明一些@property(nonatomic,retain)和@synthesize呢？然后将自动创建 getter/setter。否则，请自己定义一些 getter/setter。

Answer 4

执行以下步骤-

在第一个 ViewController 中 -

1. 创建第二个 ViewController 的对象 像 SecondViewController *sec= [[SecondViewController alloc]init]; sec.myLable=@"我的标签字符串";

   在第二个 ViewController 中 -

2. 在 .h 文件中 UILable *myLable;

   @property(nonautomic,retain)IBOutlet UILable *myLable;

   2.在.m文件中 @synthesize myLable;