Swift如何从CollectionView中的准备准备中获取单元格

Question

Im using autolayout and for the life of me cannot set the proceeding view controller image view with the previous view controller collection view cell's image. Im using

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    performSegue(withIdentifier: "openDetailView", sender: self)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "openDetailView" {
        let cell = sender as? ImageCollectionViewCell
        let detailVC = segue.destination as! DetailedImageViewController
        detailVC.imageToPresent = cell?.imageView.image

    }
}

This is the class that I have already set up to receive the image

class DetailedImageViewController : UIViewController{

var imageToPresent: UIImage!
@IBOutlet weak var imageView: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()
    imageView.image = imageToPresent
}

}

The segue performs as expected but the image DOES NOT show in detailedImageViewController. Thanks in advance.

Answer 1

You need to set the imageToPresent into a UIImageview in order to show the image.

 
 
 
  
  class DetailedImageViewController: UIViewController { @IBOutlet weak var imageView: UIImageView! var imageToPresent : UIImage! override func viewDidLoad() { super.viewDidLoad() imageView.image = imageToPresent } ...
 
  

Answer 2

It's not a best practice to avoid optional unwrapping in this case. Try to use this code and check the errors if they happen.

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "openDetailView" {
        guard let cell = sender as? ImageCollectionViewCell else {
            assertionFailure("Failed to unwrap sender. Try to set a breakpoint here and check what sender is") 
            return 
        }
        let detailVC = segue.destination as! DetailedImageViewController
        guard let cellImage = cell.imageView.image else {
            assertionFailure("The cell has no image in image view") 
            return 
        }
        detailVC.imageToPresent = cellImage
    }
}