Objective c 返回MainViewController时发出信号

在我的应用程序中，当用户按下一个按钮时，我希望在不同的视图中生成有关该主题的信息。例如，当用户按下cat按钮时，我希望出现一个显示标题和描述的新视图。然而，当他们按下dog时，它会进入相同的视图，但它会更改信息

firstViewController.h

#import "secondview.h"

@interface ViewController :UIViewController 
{
    secondview *secondviewData;
    IBOutlet UITextField *textfield;
}

@property (nonatomic, retain)secondview*secondviewData;

-(IBAction)passdata:(id)sender; 

@end

@interface secondview :UIViewController 
{
    IBOutlet UILabel *label;  
    NSString *passedValue;
}

@property (nonatomic, retain)NSString *passedValue;

-(IBAction)back:(id)sender;

@end

firstViewController.m

#import "ViewController.h"
#import "secondview.h"

@implementation ViewController

@synthesize secondviewData;

-(IBAction)passdata:(id)sender 
{
    secondview *second = [[secondview alloc] initWithNibName:nil bundle:nil];  
    self.secondviewData = second; 
    secondviewData.passedValue = @"dog Info";
    [self presentModalViewController:second animated:YES];
}

@end

#import "ViewController.h"

@implementation secondview

@synthesize passedValue;

-(IBAction)back:(id)sender 
{
    ViewController *second = [[ViewController alloc] initWithNibName:nil bundle:nil];
    [self presentModalViewController:second animated:YES];
} 

- (void)viewDidLoad
{
    label.text = passedValue;
    [super viewDidLoad];
} 

@end

secondViewController.h

#import "secondview.h"

@interface ViewController :UIViewController 
{
    secondview *secondviewData;
    IBOutlet UITextField *textfield;
}

@property (nonatomic, retain)secondview*secondviewData;

-(IBAction)passdata:(id)sender; 

@end

@interface secondview :UIViewController 
{
    IBOutlet UILabel *label;  
    NSString *passedValue;
}

@property (nonatomic, retain)NSString *passedValue;

-(IBAction)back:(id)sender;

@end

SecondViewController.m

#import "ViewController.h"
#import "secondview.h"

@implementation ViewController

@synthesize secondviewData;

-(IBAction)passdata:(id)sender 
{
    secondview *second = [[secondview alloc] initWithNibName:nil bundle:nil];  
    self.secondviewData = second; 
    secondviewData.passedValue = @"dog Info";
    [self presentModalViewController:second animated:YES];
}

@end

#import "ViewController.h"

@implementation secondview

@synthesize passedValue;

-(IBAction)back:(id)sender 
{
    ViewController *second = [[ViewController alloc] initWithNibName:nil bundle:nil];
    [self presentModalViewController:second animated:YES];
} 

- (void)viewDidLoad
{
    label.text = passedValue;
    [super viewDidLoad];
} 

@end

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当我执行此代码时，它会出现

SIGABRT

如果您的下一个视图与当前视图分离，您可以使用：

---

---------------------------还有另一种方法：--------------------------- 可以使用全局变量传递参数

创建一个类

h

m

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好吧，看看你的控制台（Cmd-Shift-R）。这很好，但我不使用故事板。那么我该怎么做呢？然后，你可以使用第二种方法：全局变量。