CustomCollectionViewLayout 在 Swift 3 上不起作用答案

【问题标题】：CustomCollectionViewLayout not working on Swift 3CustomCollectionViewLayout 在 Swift 3 上不起作用
【发布时间】：2016-12-14 04:16:53
【问题描述】：

我已经实现了UICollectionView，它可以使用下面的示例使用粘性行和列进行水平和垂直滚动：

Example

Github

应用程序可以在 Swift2 上找到，但升级后 Swift3 CustomCollectionViewLayout 给我错误

class CustomCollectionViewLayout: UICollectionViewLayout {

    let numberOfColumns = 8
    var itemAttributes : NSMutableArray!
    var itemsSize : NSMutableArray!
    var contentSize : CGSize!

    override func prepare() {
        if self.collectionView?.numberOfSections == 0 {
            return
        }

        if (self.itemAttributes != nil && self.itemAttributes.count > 0) {
            for section in 0..<self.collectionView!.numberOfSections {
                let numberOfItems : Int = self.collectionView!.numberOfItems(inSection: section)
                for index in 0..<numberOfItems {
                    if section != 0 && index != 0 {
                        continue
                    }

                    let attributes : UICollectionViewLayoutAttributes = self.layoutAttributesForItem(at: IndexPath(item: index, section: section))
                    if section == 0 {
                        var frame = attributes.frame
                        frame.origin.y = self.collectionView!.contentOffset.y
                        attributes.frame = frame
                    }

                    if index == 0 {
                        var frame = attributes.frame
                        frame.origin.x = self.collectionView!.contentOffset.x
                        attributes.frame = frame
                    }
                }
            }
            return
        }

        if (self.itemsSize == nil || self.itemsSize.count != numberOfColumns) {
            self.calculateItemsSize()
        }

        var column = 0
        var xOffset : CGFloat = 0
        var yOffset : CGFloat = 0
        var contentWidth : CGFloat = 0
        var contentHeight : CGFloat = 0

        for section in 0..<self.collectionView!.numberOfSections {
            let sectionAttributes = NSMutableArray()

            for index in 0..<numberOfColumns {
                let itemSize = (self.itemsSize[index] as AnyObject).cgSizeValue
                let indexPath = IndexPath(item: index, section: section)
                let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath)
                attributes.frame = CGRect(x: xOffset, y: yOffset, width: (itemSize?.width)!, height: (itemSize?.height)!).integral

                if section == 0 && index == 0 {
                    attributes.zIndex = 1024;
                } else  if section == 0 || index == 0 {
                    attributes.zIndex = 1023
                }

                if section == 0 {
                    var frame = attributes.frame
                    frame.origin.y = self.collectionView!.contentOffset.y
                    attributes.frame = frame
                }
                if index == 0 {
                    var frame = attributes.frame
                    frame.origin.x = self.collectionView!.contentOffset.x
                    attributes.frame = frame
                }

                sectionAttributes.add(attributes)

                xOffset += (itemSize?.width)!
                column += 1

                if column == numberOfColumns {
                    if xOffset > contentWidth {
                        contentWidth = xOffset
                    }

                    column = 0
                    xOffset = 0
                    yOffset += (itemSize?.height)!
                }
            }
            if (self.itemAttributes == nil) {
                self.itemAttributes = NSMutableArray(capacity: self.collectionView!.numberOfSections)
            }
            self.itemAttributes .add(sectionAttributes)
        }

        let attributes : UICollectionViewLayoutAttributes = (self.itemAttributes.lastObject as AnyObject).lastObject as! UICollectionViewLayoutAttributes
        contentHeight = attributes.frame.origin.y + attributes.frame.size.height
        self.contentSize = CGSize(width: contentWidth, height: contentHeight)
    }

    override var collectionViewContentSize : CGSize {
        return self.contentSize
    }

    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes! {
        return self.itemAttributes[indexPath.section][indexPath.row] as! UICollectionViewLayoutAttributes
        // Error in above return line and error is Type 'Any' has no subscript members
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        var attributes = [UICollectionViewLayoutAttributes]()
        if self.itemAttributes != nil {
            for section in self.itemAttributes {

                let filteredArray  =  (section as AnyObject).filtered(

                    using: NSPredicate(block: { (evaluatedObject, bindings) -> Bool in
                        return rect.intersects(evaluatedObject.frame)
                        // Error in above return line and error is Value of type 'Any?' has no member 'frame'
                    })
                    ) as! [UICollectionViewLayoutAttributes]


                attributes.append(contentsOf: filteredArray)

            }
        }

        return attributes
    }

    override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
        return true
    }

    func sizeForItemWithColumnIndex(_ columnIndex: Int) -> CGSize {
        var text : String = ""
        switch (columnIndex) {
        case 0:
            text = "Col 0"
        case 1:
            text = "Col 1"
        case 2:
            text = "Col 2"
        case 3:
            text = "Col 3"
        case 4:
            text = "Col 4"
        case 5:
            text = "Col 5"
        case 6:
            text = "Col 6"
        default:
            text = "Col 7"
        }

        let size : CGSize = (text as NSString).size(attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 17.0)])
        let width : CGFloat = size.width + 25
        return CGSize(width: width, height: 30)
    }

    func calculateItemsSize() {
        self.itemsSize = NSMutableArray(capacity: numberOfColumns)
        for index in 0..<numberOfColumns {
            self.itemsSize.add(NSValue(cgSize: self.sizeForItemWithColumnIndex(index)))
        }
    }
}

ContentCollectionViewCell

class ContentCollectionViewCell: UICollectionViewCell {
    @IBOutlet weak var contentLabel: UILabel!

    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

}

DateCollectionViewCell

class DateCollectionViewCell: UICollectionViewCell {
    @IBOutlet weak var dateLabel: UILabel!

    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

}

CollectionViewController

class CollectionViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
    let dateCellIdentifier = "DateCellIdentifier"
    let contentCellIdentifier = "ContentCellIdentifier"
    @IBOutlet weak var collectionView: UICollectionView!


    override func viewDidLoad() {
        super.viewDidLoad()

        self.collectionView .register(UINib(nibName: "DateCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: dateCellIdentifier)
        self.collectionView .register(UINib(nibName: "ContentCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: contentCellIdentifier)
    }


    // MARK - UICollectionViewDataSource

    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 5
    }


    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 8
    }


    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        print(indexPath.description)
        if indexPath.section == 0 {
            if indexPath.row == 0 {
                let dateCell : DateCollectionViewCell = collectionView .dequeueReusableCell(withReuseIdentifier: dateCellIdentifier, for: indexPath) as! DateCollectionViewCell
                dateCell.backgroundColor = UIColor.white
                dateCell.dateLabel.font = UIFont.systemFont(ofSize: 13)
                dateCell.dateLabel.textColor = UIColor.black
                dateCell.dateLabel.text = "Donor ID"

                return dateCell
            } else {
                let contentCell : ContentCollectionViewCell = collectionView .dequeueReusableCell(withReuseIdentifier: contentCellIdentifier, for: indexPath) as! ContentCollectionViewCell
                contentCell.contentLabel.font = UIFont.systemFont(ofSize: 13)
                contentCell.contentLabel.textColor = UIColor.black
                contentCell.contentLabel.text = "Section"

                if indexPath.section % 2 != 0 {
                    contentCell.backgroundColor = UIColor(white: 242/255.0, alpha: 1.0)
                } else {
                    contentCell.backgroundColor = UIColor.white
                }

                return contentCell
            }
        } else {
            if indexPath.row == 0 {
                let dateCell : DateCollectionViewCell = collectionView .dequeueReusableCell(withReuseIdentifier: dateCellIdentifier, for: indexPath) as! DateCollectionViewCell
                dateCell.dateLabel.font = UIFont.systemFont(ofSize: 13)
                dateCell.dateLabel.textColor = UIColor.black
                dateCell.dateLabel.text = String(indexPath.section)
                if indexPath.section % 2 != 0 {
                    dateCell.backgroundColor = UIColor(white: 242/255.0, alpha: 1.0)
                } else {
                    dateCell.backgroundColor = UIColor.white
                }

                return dateCell
            } else {
                let contentCell : ContentCollectionViewCell = collectionView .dequeueReusableCell(withReuseIdentifier: contentCellIdentifier, for: indexPath) as! ContentCollectionViewCell
                contentCell.contentLabel.font = UIFont.systemFont(ofSize: 13)
                contentCell.contentLabel.textColor = UIColor.black
                contentCell.contentLabel.text = "Section:\(indexPath.section.description) / Row: \(indexPath.row.description)"
                if indexPath.section % 2 != 0 {
                    contentCell.backgroundColor = UIColor(white: 242/255.0, alpha: 1.0)
                } else {
                    contentCell.backgroundColor = UIColor.white
                }

                return contentCell
            }
        }
    }
}

谢谢

【问题讨论】：

您在哪里遇到错误以及错误是什么，请使用该详细信息编辑您的问题。
@NiravD 第一个错误是返回 self.itemAttributes[indexPath.section][indexPath.row] as！ UICollectionViewLayoutAttributes // 错误：'Any' 类型没有下标成员第二个错误是返回 rect.intersects(evaluationObject.frame) // 错误：'Any' 类型的值？没有成员“框架”
@NiravD 如果您滚动编码部分，您可以找到它我在评论中提到了错误...
我已经告诉你编辑你的问题，请编辑你的问题而不是在评论中添加错误。
@NiravD 对不起，如果滚动代码有错误行，我已经提到了编码部分的错误。

标签： ios uicollectionview swift3 uicollectionviewlayout

【解决方案1】：

你好用这个替换你的CustomCollectionViewLayout
CustomCollectionViewLayout.swift

class CustomCollectionViewLayout: UICollectionViewLayout {
    let numberOfColumns = 8
    var itemAttributes : NSMutableArray!
    var itemsSize : NSMutableArray!
    var contentSize : CGSize!

    override func prepare() {
        if self.collectionView?.numberOfSections == 0 {
            return
        }

        if (self.itemAttributes != nil && self.itemAttributes.count > 0) {
            for section in 0..<self.collectionView!.numberOfSections {
                let numberOfItems : Int = self.collectionView!.numberOfItems(inSection: section)
                for index in 0..<numberOfItems {
                    if section != 0 && index != 0 {
                        continue
                    }

                    let attributes : UICollectionViewLayoutAttributes = self.layoutAttributesForItem(at: IndexPath(item: index, section: section))
                    if section == 0 {
                        var frame = attributes.frame
                        frame.origin.y = self.collectionView!.contentOffset.y
                        attributes.frame = frame
                    }

                    if index == 0 {
                        var frame = attributes.frame
                        frame.origin.x = self.collectionView!.contentOffset.x
                        attributes.frame = frame
                    }
                }
            }
            return
        }

        if (self.itemsSize == nil || self.itemsSize.count != numberOfColumns) {
            self.calculateItemsSize()
        }

        var column = 0
        var xOffset : CGFloat = 0
        var yOffset : CGFloat = 0
        var contentWidth : CGFloat = 0
        var contentHeight : CGFloat = 0

        for section in 0..<self.collectionView!.numberOfSections {
            let sectionAttributes = NSMutableArray()

            for index in 0..<numberOfColumns {
                let itemSize = (self.itemsSize[index] as AnyObject).cgSizeValue
                let indexPath = IndexPath(item: index, section: section)
                let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath)
                attributes.frame = CGRect(x: xOffset, y: yOffset, width: (itemSize?.width)!, height: (itemSize?.height)!).integral

                if section == 0 && index == 0 {
                    attributes.zIndex = 1024;
                } else  if section == 0 || index == 0 {
                    attributes.zIndex = 1023
                }

                if section == 0 {
                    var frame = attributes.frame
                    frame.origin.y = self.collectionView!.contentOffset.y
                    attributes.frame = frame
                }
                if index == 0 {
                    var frame = attributes.frame
                    frame.origin.x = self.collectionView!.contentOffset.x
                    attributes.frame = frame
                }

                sectionAttributes.add(attributes)

                xOffset += (itemSize?.width)!
                column += 1

                if column == numberOfColumns {
                    if xOffset > contentWidth {
                        contentWidth = xOffset
                    }

                    column = 0
                    xOffset = 0
                    yOffset += (itemSize?.height)!
                }
            }
            if (self.itemAttributes == nil) {
                self.itemAttributes = NSMutableArray(capacity: self.collectionView!.numberOfSections)
            }
            self.itemAttributes .add(sectionAttributes)
        }

        let attributes : UICollectionViewLayoutAttributes = (self.itemAttributes.lastObject as AnyObject).lastObject as! UICollectionViewLayoutAttributes
        contentHeight = attributes.frame.origin.y + attributes.frame.size.height
        self.contentSize = CGSize(width: contentWidth, height: contentHeight)
    }

    override var collectionViewContentSize : CGSize {
        return self.contentSize
    }

    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes! {
        //return self.itemAttributes[indexPath.section][indexPath.row] as! UICollectionViewLayoutAttributes
        let arr = self.itemAttributes[indexPath.section] as! NSMutableArray
        return arr[indexPath.row] as! UICollectionViewLayoutAttributes
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        var attributes = [UICollectionViewLayoutAttributes]()
        if self.itemAttributes != nil {
            for section in self.itemAttributes {

                let filteredArray  =  (section as! NSMutableArray).filtered(

                    using: NSPredicate(block: { (evaluatedObject , bindings) -> Bool in
                        let a = evaluatedObject as! UICollectionViewLayoutAttributes
                        return rect.intersects(a.frame)
                    })
                    ) as! [UICollectionViewLayoutAttributes]


                attributes.append(contentsOf: filteredArray)

            }
        }

        return attributes
    }

    override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
        return true
    }

    func sizeForItemWithColumnIndex(_ columnIndex: Int) -> CGSize {
        var text : String = ""
        switch (columnIndex) {
        case 0:
            text = "Col 0"
        case 1:
            text = "Col 1"
        case 2:
            text = "Col 2"
        case 3:
            text = "Col 3"
        case 4:
            text = "Col 4"
        case 5:
            text = "Col 5"
        case 6:
            text = "Col 6"
        default:
            text = "Col 7"
        }

        let size : CGSize = (text as NSString).size(attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 17.0)])
        let width : CGFloat = size.width + 25
        return CGSize(width: width, height: 30)
    }

    func calculateItemsSize() {
        self.itemsSize = NSMutableArray(capacity: numberOfColumns)
        for index in 0..<numberOfColumns {
            self.itemsSize.add(NSValue(cgSize: self.sizeForItemWithColumnIndex(index)))
        }
    }
}

【讨论】：

【解决方案2】：

我正在使用https://github.com/bartjacobs/StickyHeadersCollectionView

对于Swift 4 with xCode 9.2，我的问题是Swift 3 @objc inference 设置为默认或关闭时StickyHeadersCollectionViewFlowLayout 停止工作（将其设置为打开问题就消失了）但由于Swift 3 @objc inference 是应该解决的问题，所以我采取了深入研究发现我只需要在UICollectionViewDelegate 方法上使用@objc（对我来说，更准确地说只是最后一个）：

// MARK: - Collection View Delegate Flow Layout Methods
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: collectionView.bounds.width, height: self.gridCellHeight)
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
    return UIEdgeInsets.zero
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 0.0
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
    return 0.0
}

@objc func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
    if useStickyHeader {
        return CGSize(width: collectionView.bounds.width, height: self.gridCellHeight)
    } else {
        return CGSize.zero
    }
}

【讨论】：