ios - 如何更改 Collection View 单元格或按钮单击时的渐变？

Question

我在 UIView 上使用渐变，如下所示:

//the cells gradient colors
    cellgradient.frame = cell.imageView.bounds
    cellgradient.cornerRadius = cellgradient.frame.height / 2
    cellgradient.colors = [UIColor(hexString: "#ef473a")!, UIColor(hexString: "#cb2d3e")!].map { $0.cgColor }
    cellgradient.startPoint = CGPoint(x: 0.0, y: 0.5)
    cellgradient.endPoint = CGPoint(x: 1.0, y: 0.5)
    cellgradient.colors = [UIColor(hexString: "#ef473a")!, UIColor(hexString: "#cb2d3e")!]
    cell.imageView.layer.insertSublayer(cellgradient, at: 0)

现在，当我选择单元格或取消选择单元格时，我想更改当前渐变。我该怎么做？

编辑

根据答案，我执行了以下操作:

class CollectionViewCell : UICollectionViewCell
{

@IBOutlet weak var nameLabel: UILabel!
@IBOutlet weak var imageView: UIImageView!
public var checked = false
public var animated = false
public var cellgradient: CAGradientLayer = CAGradientLayer()

override var bounds : CGRect {
    didSet {
        self.layoutIfNeeded()
    }
}

override var isSelected: Bool {
    didSet {
        if isSelected {
            cellgradient.colors = [UIColor(hexString: "#ef473a")!, UIColor(hexString: "#cb2d3e")!].map { $0.cgColor }
        } else {
            cellgradient.colors = [UIColor(hexString: "#29a1e2")! , UIColor(hexString: "#485ac8")!].map { $0.cgColor }
        }
    }
}
func addthegradientLayer() {

    //the cells gradient colors
    cellgradient.frame = imageView.bounds
    cellgradient.cornerRadius = cellgradient.frame.height / 2
    cellgradient.colors = cellgradient.colors = [UIColor(hexString: "#29a1e2")! , UIColor(hexString: "#485ac8")!].map { $0.cgColor }
    cellgradient.startPoint = CGPoint(x: 0.0, y: 0.5)
    cellgradient.endPoint = CGPoint(x: 1.0, y: 0.5)
    imageView.layer.insertSublayer(cellgradient, at: 0)
}

而且它有效。现在我只剩下一个问题了:单元格的 ImageView 隐藏在渐变后面。我该如何解决这个问题？

Answer 1

我会通过subclassing UICollectionViewCell来做到这一点。您的自定义单元格类可以有一个属性来引用其渐变层。

在单元格的初始值设定项中，像现在一样将渐变层添加到 ImageView 中。 Then, override the isSelected property's didSet并修改所选或正常状态的渐变图层。