如何使用自动布局以编程方式快速设置旋转时 UICollectionView 的宽度

Question

我已经使用自动布局设置了一个带有自我调整大小的单元格的集合视图。但是，当我旋转设备时，集合视图仍然使用纵向宽度并被截断。我使用的是流布局而不是 sizeForItemAt 方法。

这是我的主视图控制器：

import UIKit

class HomeController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {

  override func viewDidLoad() {
    super.viewDidLoad()
  }

  override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    let layout = UICollectionViewFlowLayout()
    layout.estimatedItemSize = UICollectionViewFlowLayoutAutomaticSize
    layout.minimumLineSpacing = 0
    layout.scrollDirection = .vertical

    let homeCollectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
    homeCollectionView.dataSource = self
    homeCollectionView.delegate = self
    homeCollectionView.backgroundColor = .orange

    homeCollectionView.register(CellTypeOne.self, forCellWithReuseIdentifier: "CellType1")

    self.view.addSubview(homeCollectionView)
    homeCollectionView.translatesAutoresizingMaskIntoConstraints = false
homeCollectionView.leadingAnchor

.constraint(equalTo: self.view.leadingAnchor).isActive = true
    homeCollectionView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
    homeCollectionView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
    homeCollectionView.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true

  }

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

  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    // code for specific type of cells
  }

  let contents: [ContentType] = []

另外，这是我的一个细胞：

import UIKit

class CellType1: UICollectionViewCell {

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

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

  var content: Content? {
    didSet {
      sectionTextView.text = content?.sectionView
    }
  }

  let sectionTextView: UITextView = {
    let textView = UITextView()
    textView.contentInset = UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5)
//    textView.backgroundColor = .orange
    textView.translatesAutoresizingMaskIntoConstraints = false
    textView.textContainerInset = UIEdgeInsetsMake(10, 0, 20, 0)
    textView.text = "This is a Section text"
    textView.font = UIFont.systemFont(ofSize: 20, weight: .heavy)
    textView.textColor = UIColor(red: 76/255, green: 76/255, blue: 77/255, alpha: 1.0)
    textView.isEditable = false
    textView.isScrollEnabled = false
    return textView
  }()

  func setupViews() {
    addSubview(sectionTextView)

    let widthAnchorConstraint = sectionTextView.widthAnchor.constraint(equalToConstant: UIScreen.main.bounds.size.width - 16)
    widthAnchorConstraint.identifier = "sectionTextView Width Anchor Constraint"
    widthAnchorConstraint.priority = UILayoutPriority(rawValue: 1000)
    widthAnchorConstraint.isActive = true

    let topAnchorConstraint = sectionTextView.topAnchor.constraint(equalTo: topAnchor)
    topAnchorConstraint.identifier = "sectionTextView Top Anchor Constraint"
    topAnchorConstraint.isActive = true

    let leftAnchorConstraint = sectionTextView.leftAnchor.constraint(equalTo: leftAnchor)
    leftAnchorConstraint.identifier = "sectionTextView Left Anchor Constraint"
    leftAnchorConstraint.isActive = true

    let rightAnchorConstraint = sectionTextView.rightAnchor.constraint(equalTo: rightAnchor)
    rightAnchorConstraint.identifier = "sectionTextView Right Anchor Constraint"
    rightAnchorConstraint.priority = UILayoutPriority(rawValue: 999)
    rightAnchorConstraint.isActive = true

    let bottomAnchorConstraint = sectionTextView.bottomAnchor.constraint(equalTo: bottomAnchor)
    bottomAnchorConstraint.identifier = "sectionTextView Bottom Anchor Constraint"
    bottomAnchorConstraint.isActive = true
  }
}

我已经按照 Sh_Khan 的建议尝试过使用自动布局。我更新了上面的代码。但是，当我旋转时，集合视图会更新，但单元格仍保持纵向宽度设备的大小。我添加了一个屏幕截图。

我删除了带有红色标记的内容

谁能指出我正确的方向，看看 invalidateLayout() 如何在流布局上不起作用。

提前致谢

Answer 1

问题是在创建时给集合一个框架使它即使在旋转后也保持它，你可以尝试使用 autoLayout

    self.view.addSubview(homeCollectionView)
    homeCollectionView.translatesAutoresizingMaskIntoConstraints = false 
    homeCollectionView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
    homeCollectionView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
    homeCollectionView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
    homeCollectionView.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true

Answer 2

您也可以在不使用自动布局的情况下实现此目的，视图控制器会通过viewWillLayoutSubviews 或viewDidLayoutSubviews 告诉您其视图何时获得新框架（例如旋转时），这是设置所有框架的好地方/位置相关的属性。

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    homeCollectionView.frame = view.frame

    // Set frames of other views that may have change 
}

对于单元格有override layoutSubviews()