ios - 单击删除按钮，Swift，删除/删除页面 View Controller 内显示的 Controller

Question

我在 Collection View Controller 中显示图像。点击单元格时，我会将这些图像传递给页面 View Controller ，用户可以在其中选择删除或添加图像描述，如下图所示。

当用户单击删除按钮时，我会删除要删除的页面(或 View Controller )(就像在 Apple iOS 照片应用程序中单击删除按钮时看到的行为一样)。

我试图通过将空 View Controller 数组传递给 pageViewController(参见代码 A)来实现它，这导致了错误提供的 View Controller 数量 (0) 与请求的转换所需的数量 (1) 不匹配，这是有道理的。

我是否在正确的轨道上，如果是，我该如何解决这个问题？如果没有，是否有更好的方法来实现相同的目标？

代码 A:取自代码 B

pageVC.setViewControllers([], direction: .forward, animated: true, completion: nil)

代码 B:取自 UserPickedImageVC

func deleteCurrentImageObject(){

    guard let controllers = self.navigationController?.viewControllers else{
        return
    }
    for viewController in controllers {
        if viewController.className == "UserPickedImagesVC"{

            let vc              =   viewController as! UserPickedImagesVC
            let objectCount     =   vc.imageObjectsArray.count

            guard objectCount > 0 && objectCount >= itemIndex else {
                return
            }

            vc.imageObjectsArray.remove(at: itemIndex) //  Removing imageObject from the array


            if let pageVC = vc.childViewControllers[0] as? UIPageViewController {
                pageVC.setViewControllers([], direction: .forward, animated: true, completion: nil)

            }

        }
    }
} 

Storyboard

这里是完整的代码(除了一些自定义的 UICollectionViewCell):

UserPickedImagesCVC.swift

import UIKit
import ImagePicker
import Lightbox

private let imageCellId     =   "imageCell"
private let addCellId       =   "addImagesCell"

class UserPickedImagesCVC: UICollectionViewController, ImagePickerDelegate, UserPickedImagesVCProtocol {

    let imagePickerController = ImagePickerController()
    //var userPickedImages = [UIImage]()
    var userPickedImages = [ImageObject]()

    override func viewDidLoad() {
        super.viewDidLoad()

        imagePickerController.delegate = self as ImagePickerDelegate

        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false

        // Register cell classes
        self.collectionView!.register(ImageCVCell .self, forCellWithReuseIdentifier: imageCellId)
        self.collectionView!.register(ImagePickerButtonCVCell.self, forCellWithReuseIdentifier: addCellId)

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using [segue destinationViewController].
        // Pass the selected object to the new view controller.
    }
    */

    // MARK: UICollectionViewDataSource

    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        // #warning Incomplete implementation, return the number of sections
        return 1
    }


    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of items
        return userPickedImages.count + 1
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let item = indexPath.item
        print("item: \(item)")
        if item < userPickedImages.count {

            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: imageCellId, for: indexPath) as! ImageCVCell
            let userPickedImageObject = userPickedImages[item]
            //cell.showImagesButton.setImage(userPickedImage, for: .normal)

            cell.showImagesButton.setImage(userPickedImageObject.image, for: .normal)
            cell.showImagesButton.addTarget(self, action: #selector(showAlreadyPickedImages), for: .touchUpInside)
            //cell.addButton.addTarget(self, action: #selector(showAlreadyPickedImages), for: .touchUpInside)

            return cell
        }

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: addCellId, for: indexPath) as! ImagePickerButtonCVCell
        cell.addButton.addTarget(self, action: #selector(showImagePickerController), for: .touchUpInside)
        return cell


        // Configure the cell
    }


    //Function shows imagePicker that helps in picking images and capturing images with camera
    func showImagePickerController(){
        print("showImagePickerController func called")
        //self.present(imagePickerController, animated: true, completion: nil)
        self.navigationController?.pushViewController(imagePickerController, animated: true)
    }


    func showAlreadyPickedImages(){
        let vc = self.storyboard?.instantiateViewController(withIdentifier: "userPickedImagesVC") as! UserPickedImagesVC
        //vc.contentImages = userPickedImages
        vc.imageObjectsArray = userPickedImages
        vc.showingAlreadySavedImages = true
        self.navigationController?.pushViewController(vc, animated: true)
    }

    func setImagesInCells(imageObjects : [ImageObject]){
        print("setImagesInCells func called in CVC")
        userPickedImages += imageObjects
        collectionView?.reloadData()
    }


    // MARK: - ImagePickerDelegate

    func cancelButtonDidPress(_ imagePicker: ImagePickerController) {
        imagePicker.dismiss(animated: true, completion: nil)
    }

    func wrapperDidPress(_ imagePicker: ImagePickerController, images: [UIImage]) {
        guard images.count > 0 else { return }

        let lightboxImages = images.map {
            return LightboxImage(image: $0)
        }

        let lightbox = LightboxController(images: lightboxImages, startIndex: 0)
        imagePicker.present(lightbox, animated: true, completion: nil)
    }

    func doneButtonDidPress(_ imagePicker: ImagePickerController, images: [UIImage]) {
        imagePicker.dismiss(animated: true, completion: nil)

        let vc = storyboard?.instantiateViewController(withIdentifier: "userPickedImagesVC") as! UserPickedImagesVC

        //vc.contentImages = images
        vc.imageObjectsArray =  convertImagesToImageObjects(images)

        //self.present(vc, animated: true, completion: nil)
        self.navigationController?.pushViewController(vc, animated: true)
    }

    func convertImagesToImageObjects(_ imagesArray : [UIImage]) -> [ImageObject]{
        var imageObjects = [ImageObject]()
        for image in imagesArray{
            var imageObject = ImageObject()
            imageObject.image = image
            imageObject.imageDescription = ""
            imageObjects.append(imageObject)
        }
        return imageObjects
    }

}

UserPickedImagesVC.swift

import UIKit

protocol UserPickedImagesVCProtocol{
    func setImagesInCells(imageObjects : [ImageObject])
}

class ImageObject : NSObject{
    var imageDescription :  String?
    var image            :  UIImage?
}


class UserPickedImagesVC: UIViewController, UIPageViewControllerDataSource {

    var pageViewController  :   UIPageViewController?
    let placeholderText     =   "Image description.."

    var imageObjectsArray =   [ImageObject]()
    var delegate            :   UserPickedImagesVCProtocol!
    var showingAlreadySavedImages = false



    override func viewDidLoad() {
        super.viewDidLoad()
        edgesForExtendedLayout = [] // To avoid view going below nav bar
        //self.delegate = self.navigationController?.viewControllers


        // Do any additional setup after loading the view, typically from a nib.
        if showingAlreadySavedImages{
            navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Done", style: .plain, target: self, action: #selector(doneTapped))
        }else{
            navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Save", style: .plain, target: self, action: #selector(saveTapped))
        }
        // createImageAndDescriptionDict()
        createPageViewController()
        setupPageControl()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func createPageViewController(){
        print("createPageViewController func called")
        let pageController = self.storyboard?.instantiateViewController(withIdentifier: "userPickedImagesPageController") as! UIPageViewController

        pageController.dataSource = self

        if imageObjectsArray.count > 0 {
            let firstController = getItemController(0)
            let startingViewControllers = [firstController]

            pageController.setViewControllers(startingViewControllers as! [UIViewController], direction: .forward, animated: false, completion: nil)

        }

        pageViewController = pageController
        addChildViewController(pageViewController!)
        self.view.addSubview((pageViewController?.view)!)
        pageViewController?.didMove(toParentViewController: self)
    }


    // Creata the appearance of pagecontrol
    func setupPageControl(){

        let appearance = UIPageControl.appearance()
        appearance.pageIndicatorTintColor = UIColor.gray
        appearance.currentPageIndicatorTintColor = UIColor.white
        appearance.backgroundColor = UIColor.darkGray

    }



    //MARK: Delagate methods
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        let itemController = viewController as! UserPickedImageVC

        if itemController.itemIndex > 0 {
            return self.getItemController(itemController.itemIndex-1)
        }
        return nil
    }


    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let itemController = viewController as! UserPickedImageVC

        if itemController.itemIndex + 1 < imageObjectsArray.count{

            return getItemController(itemController.itemIndex+1)

        }

        return nil
    }


    func presentationCount(for pageViewController: UIPageViewController) -> Int {
        return imageObjectsArray.count
    }


    func presentationIndex(for pageViewController: UIPageViewController) -> Int {
        return 0
    }


    func currentControllerIndex() -> Int{
        let pageItemController = self.currentControllerIndex()

        if let controller = pageItemController as? UserPickedImageVC{
            return controller.itemIndex
        }

        return -1
    }


    func currentController() -> UIViewController?{
        if(self.pageViewController?.viewControllers?.count)! > 0{
            return self.pageViewController?.viewControllers?[0]
        }
        return nil
    }


    func getItemController(_ itemIndex:Int) -> UserPickedImageVC?{

        if itemIndex < imageObjectsArray.count{
            let pageItemController = self.storyboard?.instantiateViewController(withIdentifier: "userPickedImageVC") as! UserPickedImageVC

            pageItemController.itemIndex = itemIndex
            //pageItemController.imageName = imageObjectsArray[itemIndex]

            //pageItemController.imageToShow = imageObjectsArray[itemIndex]
            //pageItemController.imageToShow = getImageFromImageDescriptionArray(itemIndex, imagesAndDescriptionArray)
            pageItemController.imageObject  =   imageObjectsArray[itemIndex]
            pageItemController.itemIndex    =   itemIndex
            pageItemController.showingAlreadySavedImage = showingAlreadySavedImages
            print("Image Name from VC: \(imageObjectsArray[itemIndex])")
            return pageItemController
        }
        return nil
    }





    // Passing images back to Collection View Controller when save button is tapped

    func saveTapped(){

        let viewControllers = self.navigationController?.viewControllers
        //print("viewControllers: \(viewControllers)")

        if let destinationVC = viewControllers?[0]{
            self.delegate = destinationVC as! UserPickedImagesVCProtocol
            //self.delegate.setImagesInCells(images : imageObjectsArray)
            self.delegate.setImagesInCells(imageObjects : imageObjectsArray)
            self.navigationController?.popToViewController(destinationVC, animated: true)
        }

    }

    func doneTapped(){
        let viewControllers = self.navigationController?.viewControllers

        if let destinationVC = viewControllers?[0] {
            self.navigationController?.popToViewController(destinationVC, animated: true)
        }
    }

}

UserPickedImageVC.swift

    import UIKit
import ImageScrollView

extension UIViewController {
    var className: String {
        return NSStringFromClass(self.classForCoder).components(separatedBy: ".").last!;
    }
}

class UserPickedImageVC: UIViewController, UITextViewDelegate {



    var itemIndex : Int             = 0
    var imageDescription : String   = ""
    var imageScrollView = ImageScrollView()
    var imageDescriptionTextView : UITextView!
    var imageToShow : UIImage!

    var imageObject : ImageObject?        
    var deleteButton = UIButton(type: .system)
    var showingAlreadySavedImage = false

    var pageViewController : UIPageViewController!




    override func viewDidLoad() {
        super.viewDidLoad()


        edgesForExtendedLayout = [] // To avoid images going below the navigation bars

        pageViewController = self.parent as! UIPageViewController

        setConstraints()
        setImageAndDescription()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    //MARK: TextView delegate methods
    func textViewDidBeginEditing(_ textView: UITextView)
    {
        if (imageDescriptionTextView.text == "Image description..")
        {
            imageDescriptionTextView.text = ""
            imageDescriptionTextView.textColor = .black
        }
        imageDescriptionTextView.becomeFirstResponder() //Optional
    }

    func textViewDidEndEditing(_ textView: UITextView)
    {
        let imageDescription = imageDescriptionTextView.text

        if (imageDescription == "")
        {
            imageDescriptionTextView.text = "Image description.."
            imageDescriptionTextView.textColor = .lightGray
        }
        imageObject?.imageDescription = imageDescription
        updateImageObject(imageObject!)
        imageDescriptionTextView.resignFirstResponder()
    }



    //MARK: Private Methods
    func setImageAndDescription(){

        if let imageToDisplay = imageObject?.image{
            imageScrollView.display(image: imageToDisplay)  // Setting Image
        }
        imageDescriptionTextView.text = imageObject?.imageDescription    // Setting Description

    }

    // Function to update imageObject in UserPickedImagesVC
    func updateImageObject(_ imageObject: ImageObject){
        guard let controllers = self.navigationController?.viewControllers else{
            return
        }
        for viewController in controllers {
            if viewController.className == "UserPickedImagesVC" {
                let vc = viewController as! UserPickedImagesVC
                vc.imageObjectsArray[itemIndex] = imageObject

            }
        }
    }


    // Function to delete imageObject from UserPickedImagesVC
    func deleteCurrentImageObject(){

        guard let controllers = self.navigationController?.viewControllers else{
            return
        }
        for viewController in controllers {
            if viewController.className == "UserPickedImagesVC"{

                let vc              =   viewController as! UserPickedImagesVC
                let objectCount     =   vc.imageObjectsArray.count

                guard objectCount > 0 && objectCount >= itemIndex else {
                    return
                }

                vc.imageObjectsArray.remove(at: itemIndex) //  Removing imageObject from the array


                if let pageVC = vc.childViewControllers[0] as? UIPageViewController {
                    pageVC.setViewControllers([], direction: .forward, animated: true, completion: nil)

                }

            }
        }
    }

    func showOrHideDeleteButton(){
        if showingAlreadySavedImage{
            print("deleteButton.isNotHidden")
            deleteButton.isHidden   = false
        }else{
            print("deleteButton.isHidden")
            deleteButton.isHidden   = true
        }
    }


    func setConstraints(){
        let viewSize    =   self.view.frame.size
        let viewWidth   =   viewSize.width
        let viewHeight  =   viewSize.height
        print("viewWidth: \(viewWidth), viewHeight: \(viewHeight)")

        view.addSubview(imageScrollView)
        imageScrollView.frame = CGRect(x: 0, y: 0, width: viewWidth, height: viewHeight)
        deleteButton.tintColor = Colors.iOSBlue
        deleteButton.setImage(#imageLiteral(resourceName: "delete"), for: .normal)
        deleteButton.backgroundColor = Colors.white
        deleteButton.layer.cornerRadius = 25
        deleteButton.imageEdgeInsets = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)

        //deleteButton.currentImage.
        deleteButton.imageView?.tintColor = Colors.iOSBlue
        deleteButton.addTarget(self, action: #selector(deleteCurrentImageObject), for: .touchUpInside)
        deleteButton.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(deleteButton)
        showOrHideDeleteButton()

        imageDescriptionTextView = UITextView()
        imageDescriptionTextView.delegate = self as! UITextViewDelegate
        imageDescriptionTextView.text = "Image description.."
        imageDescriptionTextView.textColor = .lightGray

        //imageScrollView.clipsToBounds = true

        imageDescriptionTextView.translatesAutoresizingMaskIntoConstraints = false
        //imageDescriptionTextView.backgroundColor = UIColor.white.withAlphaComponent(0.8)
        imageDescriptionTextView.backgroundColor = UIColor.white
        imageDescriptionTextView.layer.cornerRadius = 5
        imageDescriptionTextView.layer.borderColor = UIColor.lightGray.cgColor
        imageDescriptionTextView.layer.borderWidth = 0.5
        view.addSubview(imageDescriptionTextView)


        let viewsDict = [
            "imageDescriptionTextView"  :   imageDescriptionTextView,
            "deleteButton"              :   deleteButton
            ] as [String:Any]

        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-5-[imageDescriptionTextView]-70-|", options: [], metrics: nil, views: viewsDict))
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[imageDescriptionTextView(50)]-5-|", options: [], metrics: nil, views: viewsDict))
        imageDescriptionTextView.sizeThatFits(CGSize(width: imageDescriptionTextView.frame.size.width, height: imageDescriptionTextView.frame.size.height))

        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[deleteButton(50)]-5-|", options: [], metrics: nil, views: viewsDict))
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[deleteButton(50)]-5-|", options: [], metrics: nil, views: viewsDict))
    }

}

Answer 1

在 UserPickedImageVC.swift 中创建回调属性

typealias DeleteCallBack = (int) -> Void

...
var itemIndex : Int             = 0
var deleteCallBack:DeleteCallBack?
...

func deleteCurrentImageObject(){
    self.deleteCallBack?(self.itemIndex)
}

在 UserPickedImagesVC.swift

func getItemController(_ itemIndex:Int) -> UserPickedImageVC?{

    if itemIndex < imageObjectsArray.count{
        let pageItemController = self.storyboard?.instantiateViewController(withIdentifier: "userPickedImageVC") as! UserPickedImageVC

        pageItemController.itemIndex = itemIndex

        pageItemController.imageObject  =   imageObjectsArray[itemIndex]
        pageItemController.itemIndex    =   itemIndex
        pageItemController.showingAlreadySavedImage = showingAlreadySavedImages
        print("Image Name from VC: \(imageObjectsArray[itemIndex])")
        pageItemController.deleteCallBack = {
            [weak self] (index) -> Void in
            self?.deleteItemAt(index: index)
        }
        return pageItemController
    }
    return nil
}

func deleteItemAt(index: Int) {
   if (imageObjectsArray.count > 1) {
       imageObjectsArray.remove(at: itemIndex)
       self.pageViewController.dataSource = nil;
       self.pageViewController.dataSource = self;
       let firstController = getItemController(0)
       let startingViewControllers = [firstController]

       pageViewController.setViewControllers(startingViewControllers as! [UIViewController], direction: .forward, animated: false, completion: nil)
   } else {
        //redirect here
        _ = navigationController?.popViewController(animated: true)
   }
}