Image isn't being sent to next view controller

1
votes

I'm trying to send an image from one view to another via a segue and display said image in an UIImageView.

The following code gets the picture and assigns it to a global UIImage variable. Excuse the graphics code, I've been playing around trying to merge an image and a text field to create a single image: 

@IBAction func sendSnap(_ sender: Any) {
    var size = CGSize(width: self.takenImage.size.width, height: self.takenImage.size.height)
    UIGraphicsBeginImageContext(size)
    let areaSize = CGRect(x: 0, y: 0, width: self.takenImage.size.width, height: self.takenImage.size.height)
    self.takenImage.draw(in: areaSize)
    var outputImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    self.finalImage = outputImage
}

I then created a segue with an identifier going from a button to the destination controller and handled the data within the prepare func: 

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "showFinal" {
        let lastVC = segue.destination as! TestingViewController
        lastVC.image = self.finalImage
    }
}

The problem I'm having is for some reason, the lastVC.image isn't being assigned with self.finalImage.

I've checked the height/width of final image to ensure it's not empty.

Here is my code for TestingViewController (destination): @IBOutlet weak var displayImage: UIImageView! var image: UIImage = UIImage()

override func viewDidLoad() {
    super.viewDidLoad()
    self.displayImage.image = image
    print(image.size.height) 
    // Do any additional setup after loading the view.
}

image.size.height is printing 0.0 in the console so I definitely know the image isn't being sent across... but I'm unsure where to go from here?

2
iosswiftxcodeuiimageviewuistoryboardsegue
Have you put a breakpoint in preparForSegue to ensure that your condition is being met and your assignment executing - i.e. is that really your segue's ID? – Ali Beadle
Also note: all those "self." before your property names are not required in Swift. – Ali Beadle
I put a simple print within the segue condition to ensure that the code was being executed. That seems to be fine. Unsure how else to test @AliBeadle – user6845426
Can you add the global variables? You can also do print(self.finalImage) inside your prepareForSegue() to see if the image is not nil – Yannick
The first breakpoint to use is on lastVC.image = self.finalImage in prepareForSeque. See if you have something for finalImage. Go from there putting breakpoints ahead or behind, depending on what you find. – dfd

2 Answers

1
votes

I'm guessing you have both

@IBAction func sendSnap(_ sender: Any) {}

and a segue assigned to the same button. When you tap the button, the segue is triggered along with prepare() and sendSnap() is called. Which one is running first?

A better approach would be to create a "named" segue, then have the button tap call sendSnap(), and at the end of sendSnap() call:

performSegue(withIdentifier: "showFinal", sender: self)
1
votes

1) In the destination View "showFinal" create a reference for your image.

var imageDisplay: UIImage? {
  didSet{
        if let image = imageDisplay {
           self.displayImage.image = image
           self.displayImage.setNeedsDisplay()
    }
}

2) Now send the this value.

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showFinal" {
    let lastVC = segue.destination as! TestingViewController
    lastVC.imageDisplay = self.finalImage
}

}