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How to set fixed gradient background on UICollectionView?

I used the following code.

CAGradientLayer* collectionRadient = [CAGradientLayer layer];
collectionRadient.bounds = self.collectionView.bounds;
collectionRadient.anchorPoint = CGPointZero;
collectionRadient.colors = [NSArray arrayWithObjects:(id)[startColor CGColor],(id)[endColor CGColor], nil];
[self.collectionView.layer insertSublayer:collectionRadient atIndex:0];

But he painted on the cells included images. therefore, the cell was not shown.

I want to draw a gradient background of a UICollectionView under the cells and fix it when viewing the scroll. Tell me.

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2 answers

Try this ... You must assign a view to use the background view.

CAGradientLayer* collectionGradient = [CAGradientLayer layer];
collectionGradient.bounds = self.view.bounds;
collectionGradient.anchorPoint = CGPointZero;
collectionGradient.colors = [NSArray arrayWithObjects:(id)[[UIColor redColor] CGColor],(id)[[UIColor greenColor] CGColor], nil];
UIView *vv = [[UIView alloc] init];
vview.backgroundView = vv;
[vview.backgroundView.layer insertSublayer:collectionGradient atIndex:0];
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In Swift 3.0

I like to start with a custom class for gradients

import UIKit
@IBDesignable
class GradientView: UIView {
    // set your start color
    @IBInspectable var startColor: UIColor = UIColor.black {didSet {updateColors ()}}
    //set your end color
    @IBInspectable var endColor:     UIColor = UIColor.white { didSet { updateColors() }}
    //you can change anchors and directions
    @IBInspectable var startLocation: Double =   0.05 { didSet { updateLocations() }}
    @IBInspectable var endLocation:   Double =   0.95 { didSet { updateLocations() }}
    @IBInspectable var horizontalMode:  Bool =  false { didSet { updatePoints() }}
    @IBInspectable var diagonalMode:    Bool =  false { didSet { updatePoints() }}
    override class var layerClass: AnyClass { return CAGradientLayer.self }
    var gradientLayer: CAGradientLayer { return layer as! CAGradientLayer }
    func updatePoints() {
        if horizontalMode {
            gradientLayer.startPoint = diagonalMode ? CGPoint(x: 1, y: 0) : CGPoint(x: 0, y: 0.5)
            gradientLayer.endPoint   = diagonalMode ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0.5)
        } else {
            gradientLayer.startPoint = diagonalMode ? CGPoint(x: 0, y: 0) : CGPoint(x: 0.5, y: 0)
            gradientLayer.endPoint   = diagonalMode ? CGPoint(x: 1, y: 1) : CGPoint(x: 0.5, y: 1)
        }
    }
    func updateLocations() {
        gradientLayer.locations = [startLocation as NSNumber, endLocation as NSNumber]
    }
    func updateColors() {
        gradientLayer.colors    = [startColor.cgColor, endColor.cgColor]
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        updatePoints()
        updateLocations()
        updateColors()
    }
}

- , , , , , .

:

let gradient = GradientView()
gradient.frame = self.view.bounds
//add to your collectionView
collectionView?.addSubview(gradient)
collectionView?.sendSubview(toBack: gradient)
self.collectionView?.backgroundView = gradient
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