Objective C 使用 ZBar 扫描二维码后无法切换视图

Question

我正在使用 XCode 4.2 开发一个检测 QR 码的应用程序。

我试图在二维码检测后切换视图，但它根本不起作用，

这里是正在使用的代码：

- (void) imagePickerController: (UIImagePickerController*) reader
 didFinishPickingMediaWithInfo: (NSDictionary*) info
{

     AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);


    // ADD: get the decode results
    id<NSFastEnumeration> results =
    [info objectForKey: ZBarReaderControllerResults];
    ZBarSymbol *symbol = nil;   
    for(symbol in results)
        break;


    NSString *string=symbol.data;
    NSString *string2=@"1234";

    if ([string isEqualToString:string2]) {

//this is the part that is not working : it doesn t load the AboutView at all

        AboutView *about = [[AboutView alloc] initWithNibName:nil bundle:nil];
        [self presentModalViewController:about animated:YES];
    }

    else{
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" 
                                                        message:@"This is not a recognized QR code!" 
                                                       delegate:self 
                                              cancelButtonTitle:@"OK" 
                                              otherButtonTitles:nil];
        [alert show];

    }

    // ADD: dismiss the controller (NB dismiss from the *reader*!)
    [reader dismissModalViewControllerAnimated: YES];
}

谢谢

Answer 1

问题是 reader 是 zbar 示例代码中呈现的视图控制器

-(void)presentReaderInViewController:(UIViewController*)vc

，并且您将 self 视为呈现的

您应该使用 reader 来呈现您的 AboutView 并仅关闭else 块中的 reader

if ([string isEqualToString:string2]) {

//this is the part that is not working : it doesn t load the AboutView at all

        AboutView *about = [[AboutView alloc] initWithNibName:nil bundle:nil];
        [reader presentModalViewController:about animated:YES];
    }

    else{
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" 
                                                        message:@"This is not a recognized QR code!" 
                                                       delegate:self 
                                              cancelButtonTitle:@"OK" 
                                              otherButtonTitles:nil];
        [alert show];
        // ADD: dismiss the controller (NB dismiss from the *reader*!)
    [reader dismissModalViewControllerAnimated: YES];
    }

您可能还想等待在警报视图的委托方法中关闭 reader （创建一个软引用并关闭该... myReader = reader ; 当您设置警报视图时）

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex{
    [myReader dismissModalViewControllerAnimated: YES];

}