ios - 从 CollectionView 的结果中显示 CollentView

Question

我在 1 个 View Controller 中有 2 个 Collection View 。我希望第二个 Collection View 根据第一个 Collection View 中项目的选择来显示其内容。我已经完成了所有工作，可以获取要显示的数据，但我认为因为 View Controller 没有重新加载，所以它没有显示数据(单元格图像、描述等)。我如何强制刷新 View 或者是否有更好的方法或在第二个 Collection View 中显示结果？

该类的完整代码如下:

import UIKit
import Parse

private let reuseIdentifierPart = "CellPart"
private let reuseIdentifierPiece = "CellPiece"

class JourneyViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {

    // passed packName from PackViewController
    var selectedPack: String!
    var selectedPart: String!

    @IBOutlet var collectionViewPart: UICollectionView!
    @IBOutlet var collectionViewPiece: UICollectionView!

    struct partStruct {
        var partName : String
        var partDescription : String
        var partTitle : String
        var partImage : PFFile
        var partID: String
    }

    struct pieceStruct {
        var pieceName : String
        //var pieceDescription : String
        //var pieceTitle : String
        var pieceImage : PFFile
    }

    var partArray = [partStruct]()
    var pieceArray = [pieceStruct]()

    var refreshView: UIViewController!


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

        // if selected pack not nil
        //--------------------------------------------- PART DISPLAY IN COLLECTION ----
        if let partsToDisplay = selectedPack {
            let partQuery = PFQuery(className: "Part")
                //have to create PFObject from selectedPack
                partQuery.whereKey("fromPack", equalTo: PFObject(outDataWithClassName: "Pack", objectId: selectedPack))
                partQuery.findObjectsInBackground(block: { (objectsArray, error) in
                    if error != nil {
                        print(error!)
                    } else if let parts = objectsArray {
                        for object in parts {

                            let arrayName = object.object(forKey: "partName") as! String
                            let arrayDescription = object.object(forKey: "partDescription") as! String
                            let arrayTitle = object.object(forKey: "partTitle") as! String
                            let arrayImage = object.object(forKey: "partImage") as! PFFile
                            //let arrayPoint = object.object(forKey: "fromPack") as! String
                            let arrayID = object.objectId as String!
                            self.partArray.append(partStruct(partName: arrayName, partDescription: arrayDescription, partTitle: arrayTitle, partImage: arrayImage, partID: arrayID!))
                        }
                        self.partArray = self.partArray.sorted{ $0.partName < $1.partName }
                        self.collectionViewPart?.reloadData()
                    }
                })
        }

    }//viewwillappear

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if collectionView == self.collectionViewPart {
            //--------------------------------------------- PIECE DISPLAY IN COLLECTION ----
            print("I selected an item in the Parts stack")
            selectedPart = self.partArray[indexPath.item].partID
            print("i selected item \(selectedPart)")

            if let piecesToDisplay = selectedPart {
                let pieceQuery = PFQuery(className: "Piece")
                //have to create PFObject from selectedPack
                pieceQuery.whereKey("fromPart", equalTo: PFObject(outDataWithClassName: "Part", objectId: selectedPart))
                pieceQuery.findObjectsInBackground(block: { (objectsArray, error) in
                    if error != nil {
                        print(error!)
                    } else if let pieces = objectsArray {
                        print(objectsArray?.count)
                        for object in pieces {

                            let arrayName = object.object(forKey: "pieceName") as! String
                            let arrayImage = object.object(forKey: "pieceImage") as! PFFile

                            self.pieceArray.append(pieceStruct(pieceName: arrayName, pieceImage: arrayImage))
                        }
                        self.pieceArray = self.pieceArray.sorted{ $0.pieceName < $1.pieceName }
                        self.collectionViewPiece?.reloadData()
                    }
                })

            } else {
                // this is for selecting somehitng in the vertical stack
                print("WERE GOING TO GO TO THE NEXT SCREEN AND PLAY THE SOUND FILE")

            }
        }
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        if collectionView == self.collectionViewPart {

            //pass this to the piece query when selected
            let selectedPart = self.partArray[indexPath.item].partName
            //--------------------------------------------- PART HOW TO DISPLAY EACH ITEM ----

            let cellPart: PartCollectionViewCell = collectionViewPart.dequeueReusableCell(withReuseIdentifier: reuseIdentifierPart, for: indexPath) as! PartCollectionViewCell

            //cellPart.labelCell.text = self.packArray[indexPath.item].packDescription
            //cellPart.labelCell.textColor = MyFunctions.UIColorFromHEX(hexValue: 0x0c1537)
            cellPart.imageCellPart.file = self.partArray[indexPath.item].partImage

            cellPart.imageCellPart.loadInBackground()

            cellPart.imageCellPart.layer.masksToBounds = true
            cellPart.imageCellPart.layer.cornerRadius = cellPart.imageCellPart.frame.height/2
            cellPart.imageCellPart.layer.borderWidth = 3
            cellPart.imageCellPart.layer.borderColor = MyFunctions.UIColorFromHEX(hexValue: 0x62aca2).cgColor

            return cellPart

        } else {
            //--------------------------------------------- PIECE HOW TO DISPLAY EACH ITEM ----

            let cellPiece: PieceCollectionViewCell = collectionViewPiece.dequeueReusableCell(withReuseIdentifier: reuseIdentifierPiece, for: indexPath) as! PieceCollectionViewCell

            //cellPiece.labelCell.text = self.packArray[indexPath.item].packDescription
            //cellPiece.labelCell.textColor = MyFunctions.UIColorFromHEX(hexValue: 0x0c1537)
            cellPiece.imageCellPiece.file = self.pieceArray[indexPath.item].pieceImage

            cellPiece.imageCellPiece.loadInBackground()

            cellPiece.imageCellPiece.layer.masksToBounds = true
            cellPiece.imageCellPiece.layer.cornerRadius = cellPiece.imageCellPiece.frame.height/2
            cellPiece.imageCellPiece.layer.borderWidth = 3
            cellPiece.imageCellPiece.layer.borderColor = MyFunctions.UIColorFromHEX(hexValue: 0x62aca2).cgColor

            return cellPiece
        }

    }
    // MARK: UICollectionViewDataSource

    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }


    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        if collectionView == self.collectionViewPart {
            return self.partArray.count
        } else {
            return self.pieceArray.count
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()

    }


}//class

Answer 1

请从主线程执行此操作。

  self.collectionViewPiece?.reloadData()
  self.collectionViewPiece?.layoutIfNeeded();