CAGradientLayer with Texture Example

ASDisplayNode+Gradient.swift

import AsyncDisplayKit

extension ASDisplayNode {
    enum GradientDirection {
        case horizontal
        case vertical
        case adjust(CGPoint, CGPoint)
        
        var points: (start: CGPoint, end: CGPoint) {
            switch self {
            case .horizontal:
                return (start: .init(x: 0.0, y: 0.5), end: .init(x: 1.0, y: 0.5))
            case .vertical:
                return (start: .init(x: 0.5, y: 0.0), end: .init(x: 0.5, y: 1.0))
            case .adjust(let start, let end):
                return (start: start, end: end)
            }
        }
    }
    
    func gradientBackgroundColor(_ colors: [CGColor], direction: GradientDirection) {
        guard !self.hasGradientLayer else { return }
        DispatchQueue.main.async {
            self.backgroundColor = .clear
            self.clipsToBounds = true
            let gradient = CAGradientLayer()
            gradient.frame = .init(origin: .zero, size: self.calculatedSize)
            gradient.colors = colors
            gradient.startPoint = direction.points.start
            gradient.endPoint = direction.points.end
            self.layer.insertSublayer(gradient, at: 0)
        }
    }
    
    var hasGradientLayer: Bool {
        return self.layer
            .sublayers?
            .filter({ $0 is CAGradientLayer }).isNotEmpty ?? false
    }
}

// Example
class TestNode: ASDisplayNode {
    struct Const {
        static let coverGradientStartColor: CGColor =
            UIColor(white: 0.0, alpha: 0.28).cgColor
        static let coverGradientEndColor: CGColor =
            UIColor(white: 0.0, alpha: 0.0).cgColor
    }
    
    let coverImageNode: ASNetworkImageNode = {
        let node = ASNetworkImageNode()
        node.contentMode = .scaleAspectFill
        node.backgroundColor = Const.coverDefaultColor
        return node
    }()
  
    override func layoutDidFinish() {
        super.layoutDidFinish()
        self.coverGradientNode
            .gradientBackgroundColor([Const.coverGradientStartColor,
                                      Const.coverGradientEndColor],
                                     direction: .vertical)
    } 
  
    override func layoutSpecThatFits(_ constrainedSize: ASSizeRange) -> ASLayoutSpec {
      // ... 
    }
}