ios - 以编程方式将 UIImage 添加到 Collection View 单元格中

Question

这是我为 Collection View 单元格自定义的类:

import UIKit

class NavBarCell: UICollectionViewCell {

    var avatarImageView: UIImageView = {
        var avatarView = UIImageView()
        avatarView.contentMode = .scaleAspectFit

        return avatarView
    }()

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

        avatarImageView = UIImageView()
        contentView.addSubview(avatarImageView)
    }

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

}

然后在我的 Controller 的 viewDidLoad 中

    let layout:UICollectionViewFlowLayout = UICollectionViewFlowLayout.init()
    navBarCollectionView.setCollectionViewLayout(layout, animated: true)
    navBarCollectionView.backgroundColor = UIColor.clear
    navBarCollectionView.register(NavBarCell.self, forCellWithReuseIdentifier: "cell")
    navBarCollectionView.delegate = self
    navBarCollectionView.dataSource = self
    layout.scrollDirection = .horizontal
    self.navigationController?.navigationBar.addSubview(navBarCollectionView)
    navBarCollectionView.reloadData()

在 cellForItem 中我有:

        let navBarCell = (collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)) as! NavBarCell

        var image : UIImage = UIImage(named: "TestImage")!
        navBarCell.avatarImageView.image = image
        navBarCell.avatarImageView.layer.borderWidth = 1
        navBarCell.avatarImageView.layer.borderColor = UIColor.getRandomColor().cgColor
        navBarCell.avatarImageView.layer.cornerRadius = 20

        return navBarCell

但是图片浏览量没有显示出来。如果我添加 navBarCell.backgroundColor = UIColor.red 则显示单元格，但不显示图像。

有什么我遗漏或没有正确实现的吗？

Answer 1

UICollectionViewCell 已经是view了，可以直接在上面添加avatarImageView:

addSubview(avatarImageView)

还可以设置约束条件，例如:

avatarImageView.translatesAutoresizingMaskIntoConstraints = false
avatarImageView.topAnchor.constraint(equalTo: topAnchor).isActive = true
avatarImageView.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
avatarImageView.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
avatarImageView.heightAnchor.constraint(equalToConstant: 300).isActive = true