数据的UIApplication

Question

我想分享的观点之间的数据...

我有应用程序的TabBar的的appdelegate：

myappdelegate.h

#import <UIKit/UIKit.h> 

@interface myappdelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> { 
    UIWindow *window; 
    UITabBarController *tabBarController; 
    NSString *result; 
} 


@property (nonatomic, retain) IBOutlet UIWindow *window; 
@property (nonatomic, retain) IBOutlet UITabBarController *tabBarController; 

@property (copy , readwrite) NSString *result; 


@end 

，如果我想用此命令调用，有提示：“可能不会回应”...

myappdelegate *dataCenter = [(myappdelegate *)[UIApplication sharedApplication] delegate]; <<may not respond 
    dataCenter.result = @"msg"; 

result_view *resultView = [[result_view alloc] initWithNibName:@"result_view" bundle:nil]; 
[self.navigationController pushViewController:resultView animated:YES]; 
[resultView release]; 

result_view.m

- (void)viewDidLoad 
{ 
    myappdelegate *dataCenter = (myappdelegate*)[[UIApplication sharedApplication]delegate]; 

    [label setText:dataCenter.result]; 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view from its nib. 
} 

程序崩溃...

Answer 1

你的代码是说，sharedApplication是类myappdelegate，这的确并不delegate回应。这样做：

(myappdelegate *)[[UIApplication sharedApplication] delegate]; 

删除警告。

---

由于Objective-C的运行时消息传递，当前（警告生成）代码不会使应用程序崩溃。崩溃在别的地方。

Answer 2

你的第一行应该是

myappdelegate *dataCenter = (myappdelegate *)[[UIApplication sharedApplication] delegate]; 

至于第二行，我不能告诉你期待发生什么。您的myappdelegate类没有result_array属性，因此当然不能设置该属性。

如果你试图设置result属性，你应该写

dataCenter.result = @"msg";