UICollectionViewCell没有填满屏幕

Question

我有一个UIViewController，其中包含一个用于垂直分页的UICollectionView。 UICollectionView（图片中的蓝色区域）固定在超级视图的顶部，而UICollectionViewCell（黄色）则不固定。我试图将UICollectionViewCell的顶部约束明确地固定在UICollectionView的顶部，但是程序崩溃了。

class HomeViewController: UIViewController, UICollectionViewDelegateFlowLayout {

  override func viewDidLoad() {
    super.viewDidLoad()
    
    let collectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: UICollectionViewFlowLayout())
    collectionView.register(FeedCell.self, forCellWithReuseIdentifier: reuseIdentifier)
    collectionView.backgroundColor = .blue
    collectionView.showsVerticalScrollIndicator = false
    collectionView.isPagingEnabled = true
    
    view.addSubview(collectionView)
    
    collectionView.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
      collectionView.topAnchor.constraint(equalTo: view.topAnchor),
      collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
      view.bottomAnchor.constraint(equalTo: collectionView.bottomAnchor),
      view.trailingAnchor.constraint(equalTo: collectionView.trailingAnchor)
    ])
    
    collectionView.dataSource = self
    collectionView.delegate = self
  }
  
  override var preferredStatusBarStyle: UIStatusBarStyle {
    .lightContent
  }
  
  // MARK: UICollectionViewDelegateFlowLayout
  
  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: view.frame.width, height: collectionView.bounds.height)
  }
  
  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
    return 0
  }
  
  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 0
  }
}

extension HomeViewController: UICollectionViewDataSource {
  func numberOfSections(in collectionView: UICollectionView) -> Int {
    1
  }


  func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    4
  }

  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath)
    cell.backgroundColor = indexPath.item % 2 == 0 ? .yellow : .orange
    
    return cell
  }
  
  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
    return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
  }
}

Answer 1

与其使用import tkinter as tk from tkinter import simpledialog ROOT = tk.Tk() ROOT.withdraw() # the input dialog USER_INP = simpledialog.askstring(title="Test", prompt="What's your Name?:") # check it out print("Hello", USER_INP) 固定到所有安全区域边缘，不如将集合视图的顶部约束固定到pinEdgesToSafeArea(to:)的顶部约束。我不知道view的来源，因此无法评论其替代品，但是您可以使用它将收藏夹视图固定在屏幕顶部：

pinEdgesToSafeArea(to:)

编辑：
根据您发布的说明，尝试将collectionView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true 设置为automaticallyAdjustsScrollIndicatorInsets ：

false

docs for more info

Answer 2

只需将您的收藏夹视图固定在View的顶部，而不是safeArea

collectionView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true;

并仅将您的收藏夹视图用于安全区域插图：

collectionView.contentInsetAdjustmentBehavior = .never;