如果要将数据从ViewControlerOne传递到ViewControlerTwo，请尝试以下操作。。。

在ViewControlerOne.h中执行以下操作：

 @property (nonatomic, strong) NSString *str1;

在ViewControllerTwo.h中执行以下操作：

 @property (nonatomic, strong) NSString *str2;

在ViewControllerTwo.m中合成str2：

@interface ViewControllerTwo ()
@end
@implementation ViewControllerTwo
@synthesize str2;

在ViewControlerOne.m中执行以下操作：

 - (void)viewDidLoad
 {
   [super viewDidLoad];

   // Data or string you wants to pass in ViewControllerTwo...
   self.str1 = @"hello world";
 }

O按钮单击事件，请执行以下操作：

-(IBAction)ButtonClicked
{
  // Navigation on buttons click event from ViewControlerOne to ViewControlerTwo with transferring data or string..
  ViewControllerTwo *objViewTwo = [self.storyboard instantiateViewControllerWithIdentifier:@"ViewControllerTwo"];
  obj.str2 = str1;
  [self.navigationController pushViewController: objViewTwo animated:YES];
}

在ViewControllerTwo.m中执行以下操作：

- (void)viewDidLoad
{
  [super viewDidLoad];
  NSLog(@"%@", str2);
}

OP没有提到视图控制器，但有很多答案都提到了，所以我想补充一下LLVM的一些新功能，以便在希望将数据从一个视图控制器传递到另一个视图，然后获取一些结果时更容易。

故事板片段、ARC和LLVM块使我比以往任何时候都容易。上面提到的一些答案已经提到了故事板和片段，但仍然依赖于授权。定义委托当然有效，但有些人可能会发现传递指针或代码块更容易。

使用UINavigator和segue，可以轻松地将信息传递给从属控制器并获取信息。ARC使传递从NSObjects派生的对象的指针变得简单，因此如果您希望从属控制器为您添加/更改/修改某些数据，请将指针传递给可变实例。块使传递动作变得容易，因此如果您希望从属控制器调用更高级别控制器上的动作，请传递一个块。您可以定义块以接受任何数量的对您有意义的参数。如果更适合的话，您还可以设计API以使用多个块。

下面是segue胶水的两个小例子。第一个简单明了地显示了传递给输入的一个参数，第二个用于输出。

// Prepare the destination view controller by passing it the input we want it to work on
// and the results we will look at when the user has navigated back to this controller's view.

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

     // This parameter gives the next controller the data it works on.
     segueHandoffWithInput:self.dataForNextController

     // This parameter allows the next controller to pass back results
     // by virtue of both controllers having a pointer to the same object.
     andResults:self.resultsFromNextController];
}

第二个示例显示为第二个参数传递回调块。我喜欢使用块，因为它将相关细节紧密地保存在源代码中——更高级别的源代码中。

// Prepare the destination view controller by passing it the input we want it to work on
// and the callback when it has done its work.

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

     // This parameter gives the next controller the data it works on.
     segueHandoffWithInput:self.dataForNextController

     // This parameter allows the next controller to pass back results.
     resultsBlock:^(id results) {
         // This callback could be as involved as you like.
         // It can use Grand Central Dispatch to have work done on another thread for example.
        [self setResultsFromNextController:results];
    }];
}

新闻视图控制器

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
  [tbl_View deselectRowAtIndexPath:indexPath animated:YES];
  News *newsObj = [newstitleArr objectAtIndex:indexPath.row];
  NewsDetailViewController *newsDetailView = [[NewsDetailViewController alloc] initWithNibName:@"NewsDetailViewController" bundle:nil];

  newsDetailView.newsHeadlineStr = newsObj.newsHeadline;

  [self.navigationController pushViewController:newsDetailView animated:YES];
}

NewsDetailViewController.h

@interface NewsDetailViewController : UIViewController
@property(nonatomic,retain) NSString *newsHeadlineStr;
@end

NewsDetailViewController.m

@synthesize newsHeadlineStr;

使用通知中心

对于Swift 3

let imageDataDict:[String: UIImage] = ["image": image]

// Post a notification
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: imageDataDict)
// `default` is now a property, not a method call

// Register to receive notification in your class
NotificationCenter.default.addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

// Handle notification
func showSpinningWheel(_ notification: NSNotification) {
    print(notification.userInfo ?? "")
    if let dict = notification.userInfo as NSDictionary? {
        if let id = dict["image"] as? UIImage {
            // Do something with your image
        }
    }
}

对于Swift 4

let imageDataDict:[String: UIImage] = ["image": image]

// Post a notification
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: imageDataDict)
// `default` is now a property, not a method call

// Register to receive notification in your class
NotificationCenter.default.addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

// Handle notification
@objc func showSpinningWheel(_ notification: NSNotification) {
    print(notification.userInfo ?? "")
    if let dict = notification.userInfo as NSDictionary? {
        if let id = dict["image"] as? UIImage {
            // Do something with your image
        }
    }
}

使用通知中心将数据从一个视图传递到另一个视图。

观察者-收听者模式效果最好。另一种解决方法是在两个类中创建相同的对象。

在类1中创建类2对象。访问要传递的数据对象，设置它们，然后按下视图控制器。

这不是这样做的。你应该使用委托。

我假设我们有两个视图控制器，ViewController1和ViewController2，这个检查是在第一个视图控制器中，当它的状态发生变化时，您需要在ViewController2中执行一些操作。为了以正确的方式实现这一点，您应该执行以下操作：

向项目添加新文件（Objective-C协议）菜单文件→ 新现在将其命名为ViewController1Delegate或任何您想要的名称，并在@interface和@end指令之间编写这些命令：

@optional

- (void)checkStateDidChange:(BOOL)checked;

现在转到ViewController2.h并添加：

#import "ViewController1Delegate.h"

然后将其定义更改为：

@interface ViewController2: UIViewController<ViewController1Delegate>

现在转到ViewController2.m，在实现中添加：

- (void)checkStateDidChange:(BOOL)checked {
     if (checked) {
           // Do whatever you want here
           NSLog(@"Checked");
     }
     else {
           // Also do whatever you want here
           NSLog(@"Not checked");
     }
}

现在转到ViewController1.h并添加以下属性：

@property (weak, nonatomic) id<ViewController1Delegate> delegate;

现在，如果您在某个事件后在ViewController2内创建ViewController1，那么您应该使用NIB文件这样做：

ViewController1* controller = [[NSBundle mainBundle] loadNibNamed:@"ViewController1" owner:self options:nil][0];
controller.delegate = self;
[self presentViewController:controller animated:YES completion:nil];

现在你都准备好了。每当您检测到ViewController1中的检查事件发生更改时，您只需执行以下操作：

[delegate checkStateDidChange:checked]; // You pass here YES or NO based on the check state of your control