如何向我的 UICollectionView 添加额外的静态单元格？

Question

我有一组照片，目前在UICollectionView 中显示。我唯一还想添加的是一个额外的静态单元格，它应该让用户可以打开相机。我使用if-else 语句来检测索引。不幸的是，控制台给了我一个超出索引的错误。

确切地说：我希望这个静态单元格位于左上角，然后是我的图像数组。我是否必须添加两个部分，还是应该注册另一个自定义单元格来完成此操作？到目前为止，我可以看到我的额外单元格，但是当被点击时它不起作用（超出索引）。

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return imageArray.count + 1
}

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

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: photoId, for: indexPath) as! PhotosCollectionViewCell

    if indexPath.row == imageArray.count {
        cell.backgroundColor = UIColor.lightGray
        cell.addGestureRecognizer(UIGestureRecognizer(target: self, action: #selector(tappedCamera)))
    } else {
        cell.imageView.image = imageArray[indexPath.item]
        cell.imageView.addGestureRecognizer(UIGestureRecognizer(target: self, action: #selector(tappedPhoto)))
    }

    return cell
}

更新代码（解决方案）

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return imageArray.count + 1
}

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

    if indexPath.row == 0 {
        let cameraCell = collectionView.dequeueReusableCell(withReuseIdentifier: cameraId, for: indexPath) as! CameraCollectionViewCell
        return cameraCell
    }

    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(tappedPhoto))
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: photoId, for: indexPath) as! PhotoCollectionViewCell

    cell.imageView.image = imageArray[indexPath.row - 1]
    cell.imageView.addGestureRecognizer(tapGesture)

    return cell
}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    if indexPath.row == 0 {
        print("Camera")
    } 
}

var startingFrame: CGRect?
var blackBackGroundView: UIView?
var selectedImageFromPicker: UIImage?
var selectedImageCompressed: UIImage?

func tappedPhoto(sender: UIGestureRecognizer) {
    if let indexPath = self.collectionView?.indexPathForItem(at: sender.location(in: self.collectionView)) {

        let imageView = self.collectionView?.cellForItem(at: indexPath)

        startingFrame = imageView?.superview?.convert((imageView?.frame)!, to: nil)

        let zoomingImageView = UIImageView(frame: startingFrame!)
        zoomingImageView.image = imageArray[indexPath.row - 1]
        zoomingImageView.isUserInteractionEnabled = true
        zoomingImageView.contentMode = .scaleAspectFill
        zoomingImageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleZoomOut)))

        if let keyWindow = UIApplication.shared.keyWindow {
            blackBackGroundView = UIView(frame: keyWindow.frame)
            blackBackGroundView?.backgroundColor = UIColor.black
            blackBackGroundView?.alpha = 0

            keyWindow.addSubview(blackBackGroundView!)
            keyWindow.addSubview(chooseLabel)
            keyWindow.addSubview(zoomingImageView)

            // Set selected image and compress
            selectedImageFromPicker = imageArray[indexPath.row - 1]
            selectedImageCompressed = selectedImageFromPicker?.resized(withPercentage: 0.1)

            chooseLabel.rightAnchor.constraint(equalTo: keyWindow.rightAnchor, constant: -25).isActive = true
            chooseLabel.bottomAnchor.constraint(equalTo: keyWindow.bottomAnchor, constant: -25).isActive = true

            UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {

                self.blackBackGroundView?.alpha = 1
                self.chooseLabel.alpha = 1

                let height = self.startingFrame!.height / self.startingFrame!.width * keyWindow.frame.width

                zoomingImageView.frame = CGRect(x: 0, y: 0, width: keyWindow.frame.width, height: height)

                zoomingImageView.center = keyWindow.center

                }, completion: {(completed) in
                    // Do nothing
            })
        }
    }
}

Answer 1

我是否必须添加两个部分，或者我应该注册另一个自定义 细胞来完成这个？

在您的情况下，只需在集合的开头添加一个单元格就足够公平了，无需多节。

你的方法应该如下实现：

1- numberOfItemsInSection 方法：应该是原样：

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return imageArray.count + 1
}

2- cellForItemAt 方法：取决于第一个单元格，如果它应该是不同的单元格：

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    // first row
    if indexPath.row == 0 {
        let cameraCell = collectionView.dequeueReusableCell(withReuseIdentifier: "cameraCell-ID", for: indexPath)

        // setup the cell...

        return cameraCell
    }

    let defaultCell = collectionView.dequeueReusableCell(withReuseIdentifier: "defaultCell-ID", for: indexPath)

    // setup default cell...

    return defaultCell
}

或者，如果您希望它是同一个单元格，但有一些版本：

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell-ID", for: indexPath)

    // first row
    if indexPath.row == 0 {
        // setup the cell as cemera cell...
    } else {
        // setup the cell as default cell...
    }

    return cell
}

其实并不需要为每个单元格添加UITapGestureRecognizer，只需实现collection​View(_:​did​Select​Item​At:​)委托方法即可：

告诉代理指定索引路径上的项目是 已选中。

3- didSelectItemAt 方法：

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    if indexPath.row == 0 { // camera cell
        // handle tapping the camera cell
    } else { // default cells
        // handle tapping the default cell

        // don't forget that:
        // getting the first element in 'imageArray' should be imageArray[indexPath.row - 1]
    }
}

希望这会有所帮助。