Question

我在UIView内为UITableViewCell设置了渐变色。第一次加载时一切正常，但在滚动后，将重新加载渐变颜色，并且每次都比实际设置条件改变位置。这是我实现渐变颜色的代码：

我该怎么办？

添加渐变层

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：

首次加载

滚动后

Answer 1

创建如下所示的自定义视图

@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

在界面构建器中将VwPercentage的自定义类设置为TriangleGradientView

将VwPercentage的类型更改为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

}

Answer 2

您可以通过使用渐变颜色数组来获得不同的渐变颜色。因为滚动UITableView时会重复使用单元格，所以渐变颜色在每个重复使用的单元格处都会改变。

初始化渐变颜色数组

let primaryGradientColorsArray = [Color1,Color2,Color3];
let secondaryGradientColorsArray = [Color1,Color2,Color3];

和在UITableView委托中

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: [primaryGradientColorsArray[indexPath.row],secondaryGradientColorsArray[indexPath.row]]), at: 1)
    cell.lblPopular.text = "POPULAR"

}else{

    cell.VwPercentage.layer.insertSublayer(gradient(frame: cell.VwPercentage.bounds, colors: [primaryGradientColorsArray[indexPath.row],secondaryGradientColorsArray[indexPath.row]]), at: 1)
    cell.lblPopular.text = "50% OFF"
}

return cell
}

滚动后，UITableViewCell中的UIView中的渐变发生了变化

2 个答案: