预期返回'UICollectionViewCell的函数中缺少返回-Swift

Question

我的cellForItem遇到了一些麻烦，因为我不知道如何同时加载3个集合视图。这是我尝试过的方法，但出现错误“在预期返回'UICollectionViewCell的函数中缺少返回”。

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

if collectionView == self.lostCollectionView {

        let lostcell: LostCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Lostcell", for: indexPath) as! LostCollectionViewCell

        lostcell.set(post: posts[indexPath.row])

        //Make TextView Clickable
        lostcell.phoneLostTextView.isEditable = false;
        lostcell.phoneLostTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber

        return lostcell
    }

    if collectionView == self.foundCollectionView {

        let foundcell: FoundCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Foundcell", for: indexPath) as! FoundCollectionViewCell

        foundcell.set(postfound: postsfound[indexPath.row])

        //Make TextView Clickable
        foundcell.phoneFoundTextView.isEditable = false;
        foundcell.phoneFoundTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber

        return foundcell
    }

    if collectionView == self.adoptionCollectionView {

        let adoptioncell: AdoptionCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Adopotioncell", for: indexPath) as! AdoptionCollectionViewCell

        adoptioncell.set(postadoption: postsadoption[indexPath.row])

        //Make TextView Clickable
        adoptioncell.phoneAdoptionTextView.isEditable = false;
        adoptioncell.phoneAdoptionTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber

        return adoptioncell
    }
}

Answer 1

您的函数有3个if。如果它们全部失败，则该函数将不返回任何内容。这就是Swift编译器抱怨的原因。

您可以在函数底部添加return UICollectionViewCell()。

此外，switch语句更适合这种情况。

Answer 2

如意义要点所述，这是由于缺少三个if的情况下缺少单元格所致。

您可以按照功能含义的建议在函数底部添加一个最终的后备单元格。

或者，您可以采用我个人更喜欢的另一种类似方法：

// Inside your **cellForItemAt** function.

switch collectionView {
    case lostCollectionView:
        // Replace this with your corresponding code.
        return LostCollectionViewCell()

    case foundCollectionView:
        // Replace this with your corresponding code.
        return FoundCollectionViewCell()

    case adoptionCollectionView:
        // Replace this with your corresponding code.
        return AdoptionCollectionViewCell()

    default:
        return UICollectionViewCell()
}

我个人认为，这种情况下的开关柜是更整洁的解决方案。

Answer 3

基本上，您需要将代码包含在这样的switch语句中：

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    switch collectionView {
    case self.lostCollectionView:
        let lostcell: LostCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Lostcell", for: indexPath) as! LostCollectionViewCell

        lostcell.set(post: posts[indexPath.row])

        //Make TextView Clickable
        lostcell.phoneLostTextView.isEditable = false;
        lostcell.phoneLostTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber

        return lostcell

    case self.foundCollectionView:
        let foundcell: FoundCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Foundcell", for: indexPath) as! FoundCollectionViewCell

        foundcell.set(postfound: postsfound[indexPath.row])

        //Make TextView Clickable
        foundcell.phoneFoundTextView.isEditable = false;
        foundcell.phoneFoundTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber

        return foundcell

    case self.adoptionCollectionView:
        let adoptioncell: AdoptionCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "Adopotioncell", for: indexPath) as! AdoptionCollectionViewCell

        adoptioncell.set(postadoption: postsadoption[indexPath.row])

        //Make TextView Clickable
        adoptioncell.phoneAdoptionTextView.isEditable = false;
        adoptioncell.phoneAdoptionTextView.dataDetectorTypes = UIDataDetectorTypes.phoneNumber

        return adoptioncell

    default:
        return UICollectionViewCell()
    }
}