Question

我的要求是在ViewController的视图顶部有一个滑块集合视图。我已经尝试了许多解决我的要求（你可以在我的集合视图中看到设置代码）。但是，我收到关于The behavior of the UICollectionViewFlowLayout is not defined的警告的时间。视图控制器是从UITabBarController内部的控制器阵列调用的，而后者又嵌入在UINavigtionController中。视图控制器包含高度为200的集合视图。我希望集合视图的每个单元格都扩展其整个宽度和高度。

警告：

2017-09-06 12:05:19.139 collectionViewSample[3686:79491] The behavior of the UICollectionViewFlowLayout is not defined because:
2017-09-06 12:05:19.139 collectionViewSample[3686:79491] the item height must be less than the height of the UICollectionView minus the section insets top and bottom values, minus the content insets top and bottom values.
2017-09-06 12:05:19.140 collectionViewSample[3686:79491] The relevant UICollectionViewFlowLayout instance is <UICollectionViewFlowLayout: 0x7ff4e4c00020>, and it is attached to <UICollectionView: 0x7ff4e5032600; frame = (0 64; 414 200); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x600000047290>; layer = <CALayer: 0x60000002d240>; contentOffset: {0, -64}; contentSize: {0, 0}> collection view layout: <UICollectionViewFlowLayout: 0x7ff4e4c00020>.
2017-09-06 12:05:19.140 collectionViewSample[3686:79491] Make a symbolic breakpoint at UICollectionViewFlowLayoutBreakForInvalidSizes to catch this in the debugger.

的AppDelegate：

    window = UIWindow(frame: UIScreen.main.bounds)
    window?.makeKeyAndVisible()
    let mainController = UITabBarController()
    let navController = UINavigationController(rootViewController: ViewController())
    mainController.viewControllers = [navController]
    window?.rootViewController = mainController

的ViewController：

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

override func viewDidLoad() {
    super.viewDidLoad()

    view.backgroundColor = .white
    setupCollectionView()
}

func setupCollectionView() {

    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .horizontal
    let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
    collectionView.translatesAutoresizingMaskIntoConstraints = false
    collectionView.scrollIndicatorInsets = .zero
    collectionView.contentInset = .zero
    collectionView.preservesSuperviewLayoutMargins = false
    collectionView.layoutMargins = .zero

    collectionView.delegate = self
    collectionView.dataSource = self
    collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "cellId")
    view.addSubview(collectionView)

    collectionView.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor).isActive = true
    collectionView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    collectionView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    collectionView.heightAnchor.constraint(equalToConstant: 200).isActive = true
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath)
    cell.backgroundColor = .green
    return cell
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 2
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 0
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
    return 0
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
    return UIEdgeInsetsMake(0, 0, 0, 0)
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: view.frame.width, height: 200)
}
}

当单元格填充了填充集合视图的整个框架的图像时，它会在导航栏的顶部留下一个小间隙。集合视图框架确实扩展到我的要求，但细胞不是。我该如何以正确的方式解决这个问题？

未定义UICollectionViewFlowLayout行为的添加集合视图的正确方法未定义警告

0 个答案: