Changing a Label in Prepareforsegue

how to use label instead of button in prepareforsegue in swift

first give the segue an identifier in storyboard and on label click or tap method use performSegueWithIdentifier("identifier", sender: self). This way the prepareForSegue gets called even on tapping label (Note: userInteraction should be enabled on label)
In your code replace self.presentViewController(vc as! UIViewController, animated: true, completion: nil) with self.performSegueWithIdentifier("identifier", sender: self)

Cannot change label text after performing segue

Because you're accessing the views of recievingVC, that means viewDidLoad() will be called (hence the name view did load). And after viewDidLoad() is called, you change the label again to 673. To fix this, you could change the text in viewWillAppear().

class StatisticsVC: UIViewController {

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        let potato = view.subviews[0] as! StatisticsView // You should just have "potato" as a property
        potato.GamesWonNum.text = "580"                  // GamesWonNum should be called "gamesWonNum"
    }
}

class TestViewController: UIViewController {

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "statsSegue" {
            segue.destination.view.subviews.forEach { ($0 as? StatisticsView)?.setLabel(data: "673") }
        }
    }
}

How to prepare for segue and send data from 1 label to another?

Change in this:

PC.label1.text = Label.text!

You are trying to assign a String to a variable of type UILabel instead of its text value.

Prepareforsegue set label

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";

Send label text data with segue in TableView in Swift

I've finally done that using this example: Passing data between two UIViewControllers using Swift and Storyboard

It's make a lot easier and helps me finally get it to work!

Thanks!

How can I set the value of a UILabel following a segue?

Your UILabel text is not being set because prepareForSegue is being called before the IBOutlet for your label on the destination view controller is connected. So at that point the label is still nil (and sending a message to nil has no effect.)

What you should do instead is to create a new property on your destination view controller to store the string, and set this property in prepareForSegue. Then in your destination view controller's viewDidLoad method, use the value of that property to set the text property of your UILabel.

Unexpectedly found nil IBOutlet in prepareForSegue

You cannot access IBOutlets of DetailViewController in prepareForSegue because they are not connected yet.

As mentioned in the comments create a String property in DetailViewController, set it in prepareForSegue and set the text property of the label in viewDidLoad or viewWillAppear of DetailViewController.

setting destinationviewcontroller's label's text in prepareForSegue throws error: unexpectedly found nil while unwrapping Optional value

This is because the outlet for myLabel will not get set in prepareForSegue, so it will be nil. Try below approach instead,

create a string var in DetailViewController like,

var labelText: String?

in prepareForSegue

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get reference to the destination view controller
    var detailVC = segue.destinationViewController as! DetailViewController
    var detailImages: Array<UIImage> = []
    detailImages.append(UIImage(named: "pup.jpg")!)
    detailImages.append(UIImage(named: "dog.png")!)
    // Set the property to the selected location so when the view for
    // detail view controller loads, it can access that property to get the feeditem obj
    detailVC.selectedLocation = _selectedLocation;
    println(_str!)
    detailVC.labelText = "hello"
}

and in viewDidLoad of DetailViewController

override func viewDidLoad() {
    super.viewDidLoad()

    self.myLabel.text = labelText
    // Do any additional setup after loading the view.
}