iOS：将对象传递给viewController错误：无法识别的选择器已发送到实例

Question

I have project where I'm using UINavegationController between to views:

I'm using the navigation controller because I'm using modal presentation (Flip)

But my problem is I'm trying to pass NSString Object to ViewControllerB: Code:

- (IBAction)goToB:(id)sender {

    [self performSegueWithIdentifier:@"goToB" sender:self];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"goToB"]) {

        BViewController *vc = (BViewController*)[segue destinationViewController];
        vc.commigFromA = @"I'm going to B!";
    }
}

But I'm getting this error:

-[UINavigationController setCommigFromA:]: unrecognized selector sent to instance 0x7ff1c4830c00

Any of you knows why or a way around this error?

I'll really appreciate your help

Answer 1

It's crashing because the destinationViewController on the segue is actually a UINavigationController , not a BViewController , and UINavigationControllers don't know about a property comingFromA . You can test this theory by replacing prepareWithSegue like this:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"goToB"]) {

        UINavigationController *nvc = (UINavigationController*)[segue destinationViewController];
        BViewController *vc = (BViewController*)nvc.viewControllers[0];
        vc.commigFromA = @"I'm going to B!";
    }
}