Question

我有一个孩子1 1 2 3 5 8 13 AAA BB KKKK AAABB BBKKKK KKKKAAABB AAABBBBKKKK 0 0 0 0 0 0 0 0 5040 5040，其中有一系列图像。当我删除任何照片时，我想将那一系列更新的图像发回给上级UICollectionViewController。同样在Child控制器中，我有一个程序化UIViewController，当我单击任何图像以将其展开时会被调用。展开图像后，用户可以单击“删除”按钮以从该阵列中删除照片。删除后，我的数组已正确更新，但是由于某些原因，我无法将其发送回父级。我尝试使用“委托和协议”将其发送回去。这是我的子控制器代码：

view

这是父级控制器：

protocol ListImagesDelegate {

    func receiveImagesUpdated(data: [String]?)
}

class ListImagesVC: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {

// Properties
    var receivedImagesPath: [String]? = []
    var fullscreenImageView = UIImageView()
    var indexOfSelectedImage = 0
    var imagesAfterDelete: [String]? = []
    var delegate: ListImagesDefectDelegate?


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

        print("imagesAfterDelete: \(imagesAfterDelete ?? [])") // I'm getting the right number of images in this array.

        delegate?.receiveImagesUpdated(data: imagesAfterDelete)
    }


...
...

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

        print("Click on photo: \(indexPath.item + 1)")

        if let imagePath = receivedImagesPath?[indexPath.item] {

            guard let selectedImage = loadImageFromDiskWith(fileName: imagePath) else {return}

            setupFullscreenImageView(image: selectedImage)

            indexOfSelectedImage = indexPath.item
        }
    }

    private func setupFullscreenImageView(image: UIImage){

        fullscreenImageView = UIImageView(image: image)
        fullscreenImageView.frame = UIScreen.main.bounds
        fullscreenImageView.backgroundColor = .black
        fullscreenImageView.contentMode = .scaleAspectFit
        fullscreenImageView.isUserInteractionEnabled = true

        self.view.addSubview(fullscreenImageView)
        self.navigationController?.isNavigationBarHidden = true
        self.tabBarController?.tabBar.isHidden = true

        let deleteButton = UIButton(frame: CGRect(x: fullscreenImageView.bounds.maxX - 50, y: fullscreenImageView.bounds.maxY - 75, width: 30, height: 40))
        deleteButton.autoresizingMask = [.flexibleLeftMargin, .flexibleBottomMargin]
        deleteButton.backgroundColor = .black
        deleteButton.setImage(UIImage(named: "trashIcon"), for: .normal)
        deleteButton.addTarget(self, action: #selector(deleteButtonTapped), for: .touchUpInside)

        fullscreenImageView.addSubview(deleteButton)
    }

    @objc func deleteButtonTapped(button: UIButton!) {
        print("Delete button tapped")

        receivedImagesPath?.remove(at: indexOfSelectedImage)

        imagesAfterDelete = receivedImagesPath

        collectionView.reloadData()

        self.navigationController?.isNavigationBarHidden = false
        self.tabBarController?.tabBar.isHidden = false
        fullscreenImageView.removeFromSuperview()
    }

我想指定我的子控制器设置了一个故事板ID（var updatedImages: [String]? = [] ... ... extension NewAlbumVC: ListImagesDelegate { func receiveImagesUpdated(data: [String]?) { print("New array: \(data ?? [])") // This print is never called. updatedImages = data } override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if segue.identifier == "goToImages" { let listImagesVC = segue.destination as! ListImagesVC listImagesVC.delegate = self } } }），并且还设置了一个从父到子（"ListImagesID"）的segue标识符。会引起任何冲突吗？

感谢您阅读。

Answer 1

似乎代表在nil这里

delegate?.receiveImagesUpdated(data: imagesAfterDelete)

为此

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

要触发，您必须具有

self.performSegue(withIdentifier:"goToImages",sender:nil)

修改：此

let listImagesDefectVC = storyboard?.instantiateViewController(withIdentifier: "ListImagesDefectID") as!     ListImagesDefectVC
listImagesDefectVC.receivedImagesPath = imagesPath   
navigationController?.pushViewController(listImagesDefectVC, animated: true)

不会触发prepareForSegue，所以添加

listImagesDefectV.delegate = self

所以最后

解决方案1：

@objc func tapOnImageView() { 
     let listImagesDefectVC = storyboard?.instantiateViewController(withIdentifier: "ListImagesDefectID") as! ListImagesDefectVC
     listImagesDefectVC.receivedImagesPath = imagesPath 
     listImagesDefectVC.delegate = self
     navigationController?.pushViewController(listImagesDefectVC, animated: true)
 }

解决方案2：

 @objc func tapOnImageView() {  
     self.performSegue(withIdentifier:"goToImages",sender:nil) 
 }

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

    if segue.identifier == "goToImages" {

        let listImagesVC = segue.destination as! ListImagesVC
        listImagesVC.receivedImagesPath = imagesPath 
        listImagesVC.delegate = self
    }
}

如何通过@objc函数在UIViewControllers之间传递数据数组

1 个答案: