Question

我试着按照这个教程： http://www.youtube.com/watch?v=L-FK1TrpUng&feature=related 00:39:00左右。

Theres一个计数器，可识别每个切换到第二个视图控制器并对其进行计数。应在第二个视图控制器上显示视图开关的数量。但它不起作用，那就是代码： Test2ViewController.h

 @interface Test2ViewController : UIViewController <UITextFieldDelegate> {

    UINavigationController *navController;
    Test21ViewController *test21View;
    NSString *text;
    IBOutlet UITextField *textField1;



}

@property(nonatomic, retain) UITextField *textField1;
@property (nonatomic, retain) UINavigationController *navController;
@property (copy) NSString *text;


-(IBAction)pushViewController:(id)sender;
@end

Test2ViewController.m：

#import“Test2ViewController.h” #import“Test21ViewController.h”

@implementation Test2ViewController

@synthesize textField1, navController, text;


-(IBAction)pushViewController:(id)sender {
    static int count = 1;
    Test21ViewController *test21ViewController = [[Test21ViewController alloc] init];
    [self.navigationController pushViewController:test21ViewController animated:YES];   
    test21ViewController.label = [NSString stringWithFormat:@"Pushed %d", count];
    count++;
}

Test21ViewController.h：

@interface Test21ViewController : UIViewController {
    UINavigationController *navController;
    NSString *label;
    IBOutlet UILabel *textLabel;
    UITextField *tF1;


}

@property (copy) NSString *label;
@property (nonatomic, retain) UINavigationController *navController;

@property(nonatomic,retain)UITextField *tF1;
-(IBAction)feldeingabe:(id)Sender;
@end

Test21ViewController.m：

@implementation Test21ViewController
@synthesize label;


- (void)viewDidLoad {

    textLabel.text = label;


}

任何想法为什么它不起作用？提前致谢

第二个问题的代码：

static int count = 1;
    Test2ViewController *test2ViewController;  
    test2ViewController.label = [NSString stringWithFormat:@"Pushed %d !!!!!", count];
    [[self navigationController] popViewControllerAnimated:NO];
    count++;

当前代码：

#import "Test21ViewController.h"

@implementation Test21ViewController
@synthesize navController, text, parentView;




-(IBAction)pushViewController2:(id)sender {
    Test2ViewController *test2ViewController;
    static int count = 1;
    test2ViewController.parentView = self;

    test2ViewController.label = [NSString stringWithFormat:@"Pushed %d !!!!!", count];
    [self.navigationController pushViewController:test2ViewController animated:YES];    count++;

}

Answer 1

你可以尝试一下：

Test21ViewController *test21ViewController = [[Test21ViewController alloc] init];  
test21ViewController.label = [NSString stringWithFormat:@"Pushed %d", count];
[self.navigationController pushViewController:test21ViewController animated:YES];

我交换了最后两行。可能是您在调用viewDidLoad之后设置了标签，因此没有在标签中设置值。

也就是说，最好将字符串作为init参数传递，而不是作为属性传递，然后在viewDidLoad中设置。

编辑：

要将其设置为init参数，您需要创建一个新的init方法来接受该参数。

- (id) initWithString:(NSString *)labelParam {
  self = [super init];
  if (self) {
    this.label = labelParam;
  }
  return self;
}

Answer 2

对于第二个问题（将字符串从子节点传递给父节点）;

Test2ViewController.h

@interface Test2ViewController : UIViewController <UITextFieldDelegate> {
    NSString *receiverPropertyFromChild;
}

@property(nonatomic, retain) NSString *receiverPropertyFromChild;

Test2ViewController.m：

-(IBAction)pushViewController:(id)sender {
    static int count = 1;
    Test21ViewController *test21ViewController = [[Test21ViewController alloc] init];   
    test21ViewController.label = [NSString stringWithFormat:@"Pushed %d", count];
    test21ViewController.parentView = self;
    [self.navigationController pushViewController:test21ViewController animated:YES];
    count++;
}

Test21ViewController.h：

@class Test2ViewController;

@interface Test21ViewController : UIViewController {
  Test2ViewController *parentView;
}

@property (nonatomic, assign) Test2ViewController *parentView;

Test21ViewController.m

-(IBAction)goToTest2ViewController:(id)sender {
    parentView.receiverPropertyFromChild = @"the text you want to pass";
    [self.navigationController popViewControllerAnimated:YES];
    count++;    
}

不能遵循该教程

2 个答案: