问题描述
我正在尝试使用集合视图制作自定义图像滑块。我希望它可以重复使用。所以我制作了单独的自定义类，其中所有 collectionView 的东西。然后从 UIViewController 调用该类，如下面的代码所示。而我的 UICollectonViewCell 只包含 imageView。
问题在于第二个单元格。 imageView 没有被添加，在第三个单元格上，它也会闪烁。我试图调试这些问题，但不能。
ImageSlider 类和 UICollectionViewCell 类在最后，带有集合视图的东西：
class ImageSlider: UIView {
var imgArr = [UIImage(named: "one.jpg"),UIImage(named: "3.jpg"),UIImage(named: "two.jpg"),UIImage(named: "4.jpg")]
var sliderCollection : UICollectionView = {
let widthRatio : Float = 16.0
let heightRatio : Float = 9.0
let collecionWidth = UIScreen.main.bounds.width - 30
let layout = UICollectionViewFlowLayout()
let collectionView = UICollectionView(frame: CGRect(x: 15,y: 100,width: collecionWidth,height: CGFloat((Float(collecionWidth)*heightRatio)/widthRatio)),collectionViewLayout: layout)
layout.scrollDirection = .horizontal
layout.minimumLinespacing = 0
layout.minimumInteritemSpacing = 0
collectionView.backgroundColor = .systemOrange
collectionView.isPagingEnabled = true
// collectionView.isScrollEnabled = true
collectionView.register(ImageSliderCell.self,forCellWithReuseIdentifier: "ImageSliderCell")
return collectionView
}()
}
extension ImageSlider: UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView,numberOfItemsInSection section: Int) -> Int {
return imgArr.count
}
func collectionView(_ collectionView: UICollectionView,cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ImageSliderCell",for: indexPath) as! ImageSliderCell
cell.imgView.image = imgArr[indexPath.item]
// cell.imgView.contentMode = .scaleAspectFit
print("cell frame : ","(\(cell.frame.width),\(cell.frame.height)")
print("imgView frame : ","(\(cell.imgView.frame.width),\(cell.imgView.frame.height)")
return cell
}
func collectionView(_ collectionView: UICollectionView,layout collectionViewLayout: UICollectionViewLayout,sizeforItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: collectionView.frame.width,height: collectionView.frame.height)
}
}
class ImageSliderCell: UICollectionViewCell {
var imgView = UIImageView()
// override func awakeFromNib() {
// self.addSubview(imgView)
// }
override init(frame: CGRect) {
super.init(frame: frame)
imgView.frame = frame
self.addSubview(imgView)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
这是 ViewController，我在其中调用 ImageSlider() 类。
class ImageSliderVC: UIViewController,UICollectionViewDelegate {
let imageSlider = ImageSlider()
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(imageSlider.sliderCollection)
imageSlider.sliderCollection.delegate = imageSlider
imageSlider.sliderCollection.dataSource = imageSlider
imageSlider.sliderCollection.reloadData()
}
}
解决方法
看起来它不能不受约束地工作，因为 UICollectionViewCell 可以用零帧创建，并将其转换为单元格内的 imageView。您需要向 imageView 添加约束以使其可见。
extension UIView {
func centerX(inView view: UIView,constant: CGFloat = 0) {
translatesAutoresizingMaskIntoConstraints = false
centerXAnchor.constraint(equalTo: view.centerXAnchor,constant: constant).isActive = true
}
func centerY(inView view: UIView,constant: CGFloat = 0) {
translatesAutoresizingMaskIntoConstraints = false
centerYAnchor.constraint(equalTo: view.centerYAnchor,constant: constant).isActive = true
}
func setDimensions(height: CGFloat,width: CGFloat) {
translatesAutoresizingMaskIntoConstraints = false
heightAnchor.constraint(equalToConstant: height).isActive = true
widthAnchor.constraint(equalToConstant: width).isActive = true
}
func setHeight(_ height: CGFloat) {
translatesAutoresizingMaskIntoConstraints = false
heightAnchor.constraint(equalToConstant: height).isActive = true
}
}
class ImageSliderCell: UICollectionViewCell {
var imgView = UIImageView()
override init(frame: CGRect) {
super.init(frame: frame)
self.addSubview(imgView)
// not sure about the right size of image ...
imgView.setDimensions(height: 100.0,width: 100.0)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}