调整 UICollectionView 标题高度？

Question

我正在尝试根据 myView 的高度调整我的 CollectionView Header 的高度。例如，我希望能够输入：

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
    return CGSize(width: view.frame.width, height: 100)
} //Instead of 100 I want to say: **myView.frame.height**

但由于我在标头类中创建了 myView 我无法访问它，我想知道是否有人可以帮助我或有更好的方法来做到这一点。我真的很感激！

这是我的代码：

class MyProfileCollectionView: UICollectionViewController, UICollectionViewDelegateFlowLayout {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.collectionView?.register(MyProfileHeader.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: headerIdentifier)
    }



    override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind:
        String, at indexPath: IndexPath) -> UICollectionReusableView {

        let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier:
            headerIdentifier, for: indexPath) as! MyProfileHeader
        header.backgroundColor = .red
        return header

    } //HERE
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        return CGSize(width: view.frame.width, height: 111)
    }

}

这是我创建 myView 的 Header 类：

  class MyProfileHeader: UICollectionReusableView, UICollectionViewDelegate {

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

            myView.widthAnchor.constraint(equalToConstant: 50).isActive = true
            myView.heightAnchor.constraint(equalToConstant: 70).isActive = true
            myView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
            myView.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
        }

//I want my headers height be equal to myView's height so if i change myView's height the headers height changes automatically.
        var myView: UIView = {
            let view = UIView()
            view.translatesAutoresizingMaskIntoConstraints = false
            view.backgroundColor = .gray
            return view
        }()

        required init?(coder aDecoder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
    }

Answer 1

不知何故，您在 MyProfileHeader 类中使用幻数作为 myview 的高度，例如 myView.heightAnchor 是 70。为了快速解决，您可以在 MyProfileHeader 内部或外部使用静态变量。

    class MyProfileHeader: UICollectionReusableView, UICollectionViewDelegate {

        static var height: CGFloat = 70.0

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

            myView.widthAnchor.constraint(equalToConstant: 50).isActive = true
            myView.heightAnchor.constraint(equalToConstant: MyProfileHeader.height).isActive = true
            myView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
            myView.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
        }
- - - - - -
}

现在您可以在布局返回中使用它：

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {

        return CGSize(width: view.frame.width, height: MyProfileHeader.height)

    }