我的印象是，UICollectionView 中的自动调整单元格大小在 iOS 8 中变得非常简单。所以，我可能在这里遗漏了一些东西。

我使用 UICollectionViewFlowLayout 的子类作为我的布局:

class BuildCollectionViewFlowLayout: UICollectionViewFlowLayout {
    required init(coder: NSCoder) {
        super.init(coder: coder)

        self.minimumLineSpacing = 1
        self.sectionInset.top = 20
        self.estimatedItemSize = CGSize(width: UIScreen.mainScreen().bounds.width, height: 90)
    }
}

然后我的 ViewController 是 UICollectionViewController 的子类，如下所示:

class ViewController: UICollectionViewController {

    let CellIdentifier = "CellIdentifier"
    let apiClient: APIClient()

    var builds:Array<JSON>? = []

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.
        self.collectionView.registerClass(BuildProjectStatusCollectionViewCell.self, forCellWithReuseIdentifier: CellIdentifier)

        self.apiClient.getProjects({ (projects, error) -> Void in
            if (error == nil) {
                dispatch_async(dispatch_get_main_queue(), {
                    self.builds = projects
                    self.collectionView.reloadData()
                })
            }
            else {

            }
        })
    }

    override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return self.builds!.count;
    }

    override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        var cell:BuildProjectStatusCollectionViewCell = self.collectionView.dequeueReusableCellWithReuseIdentifier(CellIdentifier, forIndexPath: indexPath) as BuildProjectStatusCollectionViewCell;
        cell.setup(self.builds?[indexPath.row])

        return cell;
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

最后是我的 View 单元格:

class BuildProjectStatusCollectionViewCell : UICollectionViewCell {

    var projectNameLabel: UILabel!
    var lastCommitMessageLabel: UILabel!

    override init(frame: CGRect) {
        super.init(frame: frame)

        self.initialize()
    }

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        self.initialize()
    }

    override func awakeFromNib() {
        self.initialize()
    }

    func initialize() {
        self.contentView.frame = self.bounds;
        self.contentView.autoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight

        self.projectNameLabel = UILabel(forAutoLayout: ())
        self.lastCommitMessageLabel = UILabel(forAutoLayout: ())
        self.lastCommitMessageLabel.autoresizingMask = UIViewAutoresizing.FlexibleHeight
        self.lastCommitMessageLabel.lineBreakMode = NSLineBreakMode.ByWordWrapping
        self.lastCommitMessageLabel.numberOfLines = 0

        self.contentView.addSubview(self.projectNameLabel)
        self.contentView.addSubview(self.lastCommitMessageLabel)

        setNeedsUpdateConstraints()
    }

    func setup(project:JSON!) -> Void {
        self.projectNameLabel!.text = project["name"].stringValue
        let builds: Array<JSON> = project["builds"].arrayValue!

        if builds.count == 1 {
            if builds[0]["status"].stringValue == "success" {
                self.backgroundColor = UIColor(red: 68/255, green: 175/255, blue: 105/255, alpha: 1.0)
            }
            else {
                self.backgroundColor = UIColor(red: 254/255, green: 57/255, blue: 48/255, alpha: 1.0)
            }

            self.lastCommitMessageLabel!.text = builds[0]["message"].stringValue
        }
    }

    override func preferredLayoutAttributesFittingAttributes(layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes! {
        let attr: UICollectionViewLayoutAttributes = layoutAttributes.copy() as UICollectionViewLayoutAttributes
        // Without this, it crashes. AutoLayout constraints playing around. Error: the item width must be less than the width of the UICollectionView minus the section insets left and right values.

        return attr;
    }

    override func updateConstraints() {
        super.updateConstraints()

        self.projectNameLabel.autoPinEdgesToSuperviewEdgesWithInsets(UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5), excludingEdge: ALEdge.Bottom)
        self.lastCommitMessageLabel.autoPinEdge(ALEdge.Top, toEdge: ALEdge.Bottom, ofView: self.projectNameLabel, withOffset: 10)
        self.lastCommitMessageLabel.autoPinEdgeToSuperviewEdge(ALEdge.Leading, withInset: 5)
        self.lastCommitMessageLabel.autoPinEdgeToSuperviewEdge(ALEdge.Trailing, withInset: 25)
    }
}

单元格的大小设置为布局类中的 estimatedItemSize。

我是否应该在 preferredLayoutAttributesFittingAttributes 方法中手动计算项目高度？

如果是这样， TableView 不支持 100% 自动调整行大小吗？ ( http://www.appcoda.com/self-sizing-cells/ )

最佳答案

您不需要覆盖 preferredLayoutAttributesFittingAttributes。而且您的覆盖不会调用 super，根据文档:

The default implementation of this method adjusts the size values to accommodate changes made by a self-sizing cell. Subclasses can override this method and use it to adjust other layout attributes too. If you override this method and want the cell size adjustments, call super first and make your own modifications to the returned attributes.

因此您收到的警告是合法的。它告诉您您的单元格不能比您的 Collection View 宽。这可能是因为您在设置 estimatedItemSize 时没有考虑项目间间距(默认情况下大于 0)。尝试设置小得多的尺寸。它应该有效。

如果您正在做的只是尝试自动调整一个维度的大小(即始终保持全宽)，那就别费心了。它不会起作用，因为 estimatedItemSize 意味着两个维度都可以调整大小。

关于ios - UICollectionView 自调整大小自定义单元格，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26568095/