向 DataSource 添加值时，带有 CollectionView 的 IBDesignable 崩溃

Question

我正在开发一个小型 UIView 组件，该组件在 UICollectionView 中显示主题标签，出于某些原因，我需要通过 Interface Builder 使其成为 "editable"...因此，我做到了 IBDesignable.

一切正常，除了在 prepareForInterfaceBuilder 中我试图将一个对象附加到 datasource，因此当集成到情节提要中的某处时列表会显示一些内容。

到达第 self.hashtags.append(hashtag) 行时崩溃。如果我删除这一行，视图将在故事板上正确呈现，如果我再次放置它 ---> 崩溃...在我进行了所有调试之后，似乎 IB 无法访问此属性或看到它为零.

我无法调试 任何东西，Xcode 不允许我调试 Storyboard > Editor 中的选定视图（在 macOS Mojave 上会导致错误）。我的视图没有 .xib，并且都需要 init 的

我还检查了 Console.app 中的日志，但什么也没有。这是 Storyboard 给出的主要错误消息：

Main.storyboard：错误：IB Designables：无法呈现和更新 PublishViewController 的自动布局状态 (tSg-9E-Vz3)：代理抛出异常。

代码（重要的）

@IBDesignable
class HashtagView: UIView {

    @IBOutlet weak var height: NSLayoutConstraint?

    var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        let view = UICollectionView(frame: .zero, collectionViewLayout: layout)
        return view
    }()

    open var hashtags: [HashTag] = []

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

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }

    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        setup()

        self.hashtags.append(HashTag(word: "it works")) < CRASH
        self.collectionView.reloadData()
        self.layoutSubviews()
    }
}

设置函数()

func setup() {
    self.backgroundColor = UIColor.clear
    self.backgroundColor = UIColor.Custom.ligthGray
    self.clipsToBounds = true
    self.layer.cornerRadius = self.cornerRadius

    let alignedFlowLayout = AlignedCollectionViewFlowLayout(horizontalAlignment: .left, verticalAlignment: .top)
    alignedFlowLayout.minimumLineSpacing = 5.0
    alignedFlowLayout.minimumInteritemSpacing = 7.0
    alignedFlowLayout.sectionInset = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)

    self.collectionView.collectionViewLayout = alignedFlowLayout
    self.collectionView.translatesAutoresizingMaskIntoConstraints = false

    self.collectionView.delegate = self
    self.collectionView.dataSource = self
    self.collectionView.backgroundColor = UIColor.clear
    self.collectionView.isScrollEnabled = false

    self.collectionView.register(UINib(nibName: "RemovableTagCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "RemovableTagCollectionViewCell")

    self.addSubview(self.collectionView)

    self.collectionView.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
    self.collectionView.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
    self.collectionView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
    self.collectionView.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
}

Answer 1

所以设置绝对是相关的。显然 IB 在尝试为您的 UICollectionView 加载您的单元格时崩溃了。它无法加载 Nib 文件。它与刚刚同时崩溃的追加没有任何关系。我复制了您的问题，然后用代码创建了一个单元格，一切正常。如果这有助于回答您的问题，请告诉我。所有必需的代码都在那里。

import UIKit

struct HashTag {
    var word:String?
}

class HashCollectionViewCell: UICollectionViewCell {

    lazy var wordLabel : UILabel = {
        let lbl = UILabel(frame: self.bounds)
        lbl.font = UIFont.systemFont(ofSize: 17)
        lbl.textColor = .black
        return lbl
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.addSubview(wordLabel)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.addSubview(wordLabel)
    }

    func configureWithTag(tag:HashTag) {
        wordLabel.text = tag.word
    }

}

@IBDesignable
class HashTagView: UIView {

    private var sizingLabel = UILabel(frame: .zero)
   lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        let view = UICollectionView(frame: self.bounds, collectionViewLayout: layout)
        view.autoresizingMask = [.flexibleWidth,.flexibleHeight]
        return view
    }()

    var hashtags: [HashTag] = [HashTag(word: "this works")]

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

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }


    func setup(){
        sizingLabel.font = UIFont.systemFont(ofSize: 17)

        self.addSubview(collectionView)
        collectionView.frame = self.bounds
        collectionView.backgroundColor = self.backgroundColor
        collectionView.register(HashCollectionViewCell.self, forCellWithReuseIdentifier: "hashCell")
        self.addSubview(collectionView)

        for x in 0..<10{
            addHashTag(tag: "This is more \(x)")
        }

        collectionView.delegate = self
        collectionView.dataSource = self
    }

    func addHashTag(tag:String){
        let newHash = HashTag(word: tag)
        self.hashtags.append(newHash)
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        collectionView.frame = self.bounds
    }

}

extension HashTagView: UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout{
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return hashtags.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "hashCell", for: indexPath) as? HashCollectionViewCell{
            let tag = self.hashtags[indexPath.item]
            cell.configureWithTag(tag: tag)
            return cell
        }
        return UICollectionViewCell()
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let tag = self.hashtags[indexPath.item]
        sizingLabel.text = tag.word
        sizingLabel.sizeToFit()
        return sizingLabel.frame.size
    }
}

结果：

2) 您可以将 nib 加载到以编程方式创建的单元格中，它会起作用。 对于作为编程单元格的部分，示例看起来像这样。

在单元格内使用 nib 的带有视图扩展的单元格代码：

extension UIView {
    func loadNib() -> UIView {
        let bundle = Bundle(for: type(of: self))
        let nibName = type(of: self).description().components(separatedBy: ".").last!
        let nib = UINib(nibName: nibName, bundle: bundle)
        return nib.instantiate(withOwner: self, options: nil).first as! UIView
    }
}

class HashCollectionViewCell: UICollectionViewCell {

    var hashTagNib : HashTagNibView?

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

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }

    func setup(){
        if let htn = HashTagNibView().loadNib() as? HashTagNibView{
            hashTagNib = htn
            hashTagNib?.frame = self.bounds
            hashTagNib?.autoresizingMask = [.flexibleWidth,.flexibleHeight]
           self.addSubview(htn)
        }

    }

    func configureWithTag(tag:HashTag) {
        if let htn = hashTagNib{
            htn.hashTagButtonLabel.setTitle(tag.word, for: .normal)
        }
    }

笔尖设置如下所示：

这可能会给你更多的灵活性，具体取决于你在做什么，结果是相似的，除了在 nib 示例中我使用了 UIButton。

向 DataSource 添加值时，带有 CollectionView 的 IBDesignable 崩溃

IBDesignable with CollectionView crashes when add value to DataSource

xcode

interface-builder

ios

swift

ibdesignable