Question

I have a prepareforsegue method that takes a picture and shows it on a different viewcontroller. So I need to set a label on the secondviewcontroller at the same time that the pictures is showing, later I’ll do a random word generator on that label but right now I just need to set the label. I tried putting it inside the prepareforsegue method but it gives me an error. Here’s all my code:

//ViewController.m   

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

            UIImagePickerController *controller = [segue destinationViewController];
            controller.sourceType = [segue.identifier isEqualToString:@"LibrarySegue"] ?  UIImagePickerControllerSourceTypePhotoLibrary : UIImagePickerControllerSourceTypeCamera;
            controller.delegate = self;


        }
        else if([segue.identifier isEqualToString:@"ShowImageViewController"]){

            UIImage *image = (UIImage*)sender;
            ShowImageViewController *viewController = segue.destinationViewController;
            viewController.pickedImage = image;

            UILabel *label = (UILabel *) sender;
            ShowImageViewController *vc = segue.destinationViewController;
            vc.cap = label;
           //I tried to set the label here
            label.text = @"Hello";

        }
    }

    -(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
        [self dismissViewControllerAnimated:YES completion:nil];
    }

    -(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
        UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
        [self dismissViewControllerAnimated:YES completion:^{
            picker.delegate = nil;
            [self performSegueWithIdentifier:@"ShowImageViewController" sender:image];
        }];
    }

//SeconViewController.h
@property(nonatomic, strong) UIImage *pickedImage;
@property (weak, nonatomic) IBOutlet UIImageView *pickedImageView;
@property(nonatomic, retain) IBOutlet UILabel *cap;

//SecondViewController.m

-(void)viewWillAppear:(BOOL)animated{
    self.pickedImageView.image = self.pickedImage;
}

Answer 1

You’re casting the sender to two very different things.

UIImage *image = (UIImage*)sender;
ShowImageViewController *viewController = segue.destinationViewController;
viewController.pickedImage = image;

UILabel *label = (UILabel *) sender;
ShowImageViewController *vc = segue.destinationViewController;
vc.cap = label;
label.text = @"Hello";

You cannot cast a UIImage to a UILabel and expect things to go smoothly. In prepareForSegue, you send along an image, not a label.

Can you just change the bottom four lines to:

viewController.cap.text = @"Hello";

In this case, another option would be to define a new property in ShowImageViewController as you did for the image.

//SecondViewController.h
@property(nonatomic, strong) UIImage *pickedImage;
@property (weak, nonatomic) IBOutlet UIImageView *pickedImageView;
@property(nonatomic, retain) IBOutlet UILabel *cap;
@property (nonatomic, strong) NSString pickedLabel; //New property

-(void)viewWillAppear:(BOOL)animated{
    self.pickedImageView.image = self.pickedImage;
    self.cap.text = self.pickedLabel;
}

And then in prepareForSegue

UIImage *image = (UIImage*)sender;
ShowImageViewController *viewController = segue.destinationViewController;
viewController.pickedImage = image;
viewController.pickedLabel = @"Hello";