如何在集合视图单元格上显示coreData（swift4）

Question

如果标签显示在下面，我的代码可以正常工作。但是在这个函数中，我收到错误消息Missing return in a function is return return＆＃39; UICollectionViewCell＆＃39;。将返回单元格放在for循环中不起作用。

       import UIKit

class collectionVIEW: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {

        var users = [User]()
    @IBOutlet var theIssues: UICollectionView!
    override func viewDidLoad() {
        super.viewDidLoad()

//        users = cdHandler.fetchObject()!

    }


    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

        return users.count

    }

    func getDefaultCell() -> UICollectionViewCell{
                    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! whyCollectionViewCell
    }
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {


        if cdHandler.fetchObject() != nil {
            users = cdHandler.fetchObject()!

            for c in users {

                let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! whyCollectionViewCell
                cell.general.text = "\((cell.general.text)!)+\((c.userName)!)"

                return cell
            }

        } else {
            return getDefaultCell()
        }



    }




}

Answer 1

cellForItemAt方法期望在所有情况下返回UICollectionViewCell。在else条件下，返回默认单元格，如下所示： -

  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    if cdHandler.fetchObject() != nil {
        users = cdHandler.fetchObject()!

        for c in users {

       let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! whyCollectionViewCell
            cell.general.text = "\((cell.general.text)!)+\((c.userName)!)"

        return cell
                }

        }else{
           return getDefaultCell()
}

注意：-Register集合视图，标识为defaultCcell

func getDefaultCell() -> UICollectionViewCell{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "defaultCcell", for: indexPath) as! UICollectionViewCell
return cell 
}