Objective C - 将 NSString 传递给另一个视图控制器返回 null

Question

我想将包含注释标题的 NSString ("theData") 传递给另一个视图控制器，当我在第一个视图控制器中使用 NSLog 时，它会 return 正确的标题，但是，当我尝试在下一个视图控制器的文本标签中显示它时，它显示 (null) 并且当我在第二个视图控制器中使用 NSLog 时，它也没有 return 任何东西。

UbicacionVC.m

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.mapView.delegate = self;
self.searchBar.delegate = self;


 }


- (void)mapView:(MKMapView *)mapView didSelectAnnotationView:(MKAnnotationView *)view
   {
    for (MKPointAnnotation *annotation in mapView.annotations) {
         if (view.annotation != annotation) {
        [mapView removeAnnotation:annotation];
        NSLog(@"yes!");

    }

}
NSString *theData = view.annotation.title;
DireccionVC *direccionVC = [[DireccionVC alloc] init];
direccionVC.theData = theData;


}
- (IBAction)Continue:(id)sender {
UIViewController *VC = [self.storyboard instantiateViewControllerWithIdentifier:@"DireccionVC"];
[self.revealViewController setFrontViewController:VC animated:YES];



 }

DireccionVC.h

 @interface DireccionVC : UIViewController{
     NSString *theData;

 }

 @property (nonatomic, retain) NSString *theData;


 @end

DireccionVC.m

 @interface DireccionVC ()
 @end

 @implementation DireccionVC

 @synthesize theData;
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.     
self.lblDireccion.text = [NSString stringWithFormat:@"%@", theData];

}

Answer 1

试试这个。替换

- (IBAction)Continue:(id)sender {
    UIViewController *VC = [self.storyboard instantiateViewControllerWithIdentifier:@"DireccionVC"];
    [self.revealViewController setFrontViewController:VC animated:YES];
 }

与

- (IBAction)Continue:(id)sender {
    DireccionVC *VC = [self.storyboard instantiateViewControllerWithIdentifier:@"DireccionVC"] as! DireccionVC;
    VC.theData = theData;
    [self.revealViewController setFrontViewController:VC animated:YES];
 }

只需确保故事板中的 DirectionVC 实际上是 DirectionVC class。

Objective C - 将 NSString 传递给另一个视图控制器返回 null

Objective C - Passing NSString to another view controller is returning null

objective-c

nsstring