nil when set new image to the same imageView

Question

I am using unsplash.it to download some images to an imageView. When i click the screen image is downloaded from unsplash and refresh imageview. When I call function downloadImage() from table view controller application crashes at self.screenImg.image = image because of fatal error: unexpectedly found nil while unwrapping an Optional value. why is this happening?

I guess i should set screenImg to nil, and then set the new image from unsplash in screenImg, but even after this the application keeps crashing. how can i solve it? image reference here

MainViewController

@IBOutlet weak var screenImg: UIImageView!
@IBAction func changeImgBtn(_ sender: AnyObject) {
print("screen pressed")
    downloadImage()


}


func downloadImage() {

    let pictureURL = URL(string: "https://unsplash.it/g/750/1334/?random")!

           let session = URLSession(configuration: .default)


    let downloadPicTask = session.dataTask(with: pictureURL) { (data, response, error) in
        // The download has finished.
        if let e = error {
            print("Error downloading picture: \(e)")
        } else {

            if let res = response as? HTTPURLResponse {
                print("Downloaded cat picture with response code \(res.statusCode)")
                if let imageData = data {

                    let image = UIImage(data: imageData)

                    DispatchQueue.main.async() {
                        self.screenImg.image = image


                    }

                } else {
                    print("Couldn't get image: Image is nil")
                }
            } else {
                print("Couldn't get response code for some reason")
            }
        }
    }

    downloadPicTask.resume()
}

TableViewController

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    if indexPath.row == 1 {

        if mainViewController.screenImg?.image == nil {
            print("it is nil")
        } else {
            print("it is not nil")
        }
        mainViewController.screenImg?.image = nil
        mainViewController.downloadImage()
        print("screen is pressed from menu")
        navigationController?.popViewController(animated: true)
        dismiss(animated: true, completion: nil)



    }

I checked with an if. Value is nil, but when i go to the preview i can actually see that the image is downloaded. — dan, Aug 13 '17 at 19:35
http://imgur.com/a/W2X4f when i click on the image preview i can see the next image. — dan, Aug 13 '17 at 19:48
if i use if let app is not crashing but the image still doesnt update... — dan, Aug 13 '17 at 20:48
Check my answer on this : https://stackoverflow.com/a/37019507/3400991 — Shobhakar Tiwari, Aug 13 '17 at 21:05
it is exactly how my code is working, but everytime i call my code from tableviewcontroller to change imageview in mainviewcontroller, the image doesn't change even if it's there. — dan, Aug 13 '17 at 23:24
Did you change the name of your image view at any point and forget to delete and reconnect the outlet? — Nick Kohrn, Aug 14 '17 at 02:56
I have all my outlets connected. One idea could be that maybe something happens when i call the function in the tableView from the MainViewControlller? I just want to click on the cell and change the image. — dan, Aug 14 '17 at 10:23

nil when set new image to the same imageView

0 Answers0