ios - 滚动后 UITableViewCell 中的 UIView 中的渐变发生变化

Question

我在 UITableViewCell 中为 UIView 设置了渐变颜色。第一次加载时一切正常，但滚动后，渐变颜色再次加载，每次都比实际设置条件更改位置。这是我实现渐变颜色的代码:

我该怎么办？

添加渐变图层

func gradient(frame:CGRect,colors: [CGColor]) -> CAGradientLayer {
    let layer = CAGradientLayer()
    layer.frame = frame
    layer.startPoint = CGPoint(x: 1.0, y: 0.0)
    layer.endPoint = CGPoint(x: 0.0, y: 1.0)
    layer.locations = [0.5,0.35]
    layer.colors = colors
    return layer
}

UITableViewCell 类

class AllOfferlistCell: UITableViewCell {

    @IBOutlet weak var lbltitle: UILabel!
    @IBOutlet weak var lblPopular: UILabel!
    @IBOutlet weak var VwPercentage: UIView!   
}

tableView cellForRowAtindexPath

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! AllOfferlistCell

    cell.lbltitle.text = "Index \(indexPath.row)"

    if self.DataArray[indexPath.row].Flag == "1"{

        cell.VwPercentage.layer.insertSublayer(gradient(frame: cell.VwPercentage.bounds, colors: [UIColor.red.cgColor,UIColor.white.cgColor]), at: 1)
        cell.lblPopular.text = "POPULAR"

    }else{

        cell.VwPercentage.layer.insertSublayer(gradient(frame: cell.VwPercentage.bounds, colors: [UIColor.blue.cgColor,UIColor.white.cgColor]), at: 1)
        cell.lblPopular.text = "50% OFF"
    }

    return cell
}

输出:

第一次加载

滚动后

Answer 1

像下面这样创建自定义 View

@IBDesignable class TriangleGradientView: UIView {
    @IBInspectable var topColor: UIColor = UIColor.red {
        didSet {
            setGradient()
        }
    }
    @IBInspectable var bottomColor: UIColor = UIColor.blue {
        didSet {
            setGradient()
        }
    }
    
    override class var layerClass: AnyClass {
        return CAGradientLayer.self
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        setGradient()
    }
    
    private func setGradient() {
        (layer as! CAGradientLayer).colors = [topColor.cgColor, bottomColor.cgColor]
        (layer as! CAGradientLayer).startPoint = CGPoint(x: 1.0, y: 0.0)
        (layer as! CAGradientLayer).endPoint = CGPoint(x: 0.0, y: 1.0)
        (layer as! CAGradientLayer).locations = [0.5,0.35]
    }

}

使用

1. 在界面生成器中将 VwPercentage 的自定义类设置为 TriangleGradientView

2. 将 VwPercentage 类型更改为 TriangleGradientView。

   func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
       let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! AllOfferlistCell
       cell.lbltitle.text = "Index \(indexPath.row)"
       if self.DataArray[indexPath.row].Flag == "1"{
           cell.VwPercentage.topColor = .red
           cell.lblPopular.text = "POPULAR"
       }else{
           cell.VwPercentage.topColor = .blue
           cell.lblPopular.text = "50% OFF"
       }
       cell.VwPercentage.bottomColor = .white
       return cell
   }