Adding a CGGradient as sublayer to UILabel hides the text of label

Question

I want to add the gradient as a background to label. I used the following code to acheive that. but the problem is that though the gradient color appears on the label, but the text is not visible. please help

lblPatientDetail.text=PatientsDetails;

lblPatientDetail.textColor=[UIColor blackColor];  

CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = lblPatientDetail.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor whiteColor] CGColor],(id)[[UIColor colorWithRed:255/255.0 green:239/255.0 blue:215/255.0 alpha:1.0] CGColor],nil];  

[lblPatientDetail.layer addSublayer:gradient];

lblPatientDetail.backgroundColor=[UIColor clearColor];

Answer 1

Inserting a sublayer to a UILabel hides the text, so the best way to get what you want is to add the label and gradient layer to a UIView.

UIView *gradientLabelView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 30)];

CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = gradientLabelView.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor whiteColor] CGColor],(id)[[UIColor colorWithRed:255/255.0 green:239/255.0 blue:215/255.0 alpha:1.0] CGColor],nil];

[gradientLabelView.layer addSublayer:gradient];

lblPatientDetail.frame = gradientLabelView.bounds;
lblPatientDetail.backgroundColor = [UIColor clearColor];
[gradientLabelView addSubview:lblPatientDetail];

[self addSubview:gradientLabelView];

Answer 2

The suggested answer with the UILabel inside a UIView works. Apparently UILabels cannot have text within them after giving the background a gradient color background... don't know why....

But heres the full code for the solution.... hope this helps someone :)

UIView *EnvironmentalsLabelView = [[UIView alloc] initWithFrame:CGRectMake(0, 300, 320, 20)];
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = EnvironmentalsLabelView.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor darkGrayColor]CGColor], (id)[[UIColor blackColor]CGColor], nil];
[EnvironmentalsLabelView.layer insertSublayer:gradient atIndex:0];
[scroller addSubview:EnvironmentalsLabelView];

UILabel *EnviornmentalsLabelText = [[UILabel alloc] initWithFrame:EnvironmentalsLabelView.bounds];
[EnviornmentalsLabelText setFont:[UIFont fontWithName:@"Arial-BoldMT" size:12.0f]];
EnviornmentalsLabelText.textAlignment = NSTextAlignmentCenter;
EnviornmentalsLabelText.backgroundColor = [UIColor clearColor];
EnviornmentalsLabelText.text = @"Environmental Benefits";
[EnvironmentalsLabelView addSubview:EnviornmentalsLabelText];

Happy coding!!!!

Answer 3

One more additional think to correct answer. If you are use autolayouts for place your custom view you can get this problem - http://prntscr.com/5tj7bx

So your view has a different size then subView - UILabel and subLayer - gradient layer.

I solve this problem by add one method

class wResultView: UIView {
var label = UILabel()
var gradientLayer = CAGradientLayer()

override func layoutSubviews() {
    gradientLayer.frame = self.bounds
    label.frame = self.bounds
}
......

Answer 4

The solution which implies creation of UIView is not very convenient for regular use. Let me suggest a reusable solution for this.

import UIKit

@IBDesignable
class GradientTextLabel: UILabel {
    // MARK: - Public vars
    @IBInspectable var startColor: UIColor = .red { didSet { setNeedsDisplay() } }
    @IBInspectable var midColor: UIColor = .orange { didSet { setNeedsDisplay() } }
    @IBInspectable var endColor: UIColor = .yellow { didSet { setNeedsDisplay() } }
    @IBInspectable var vertical = false { didSet { setNeedsDisplay() } }
    
    // MARK: - Lifecycle methods
    override func layoutSubviews() {
        super.layoutSubviews()
        
        let gradient = getGradientLayer(bounds: bounds)
        textColor = gradientColor(bounds: bounds, gradientLayer: gradient)
    }
    
    override func prepareForInterfaceBuilder() {
        setNeedsDisplay()
    }
    
    // MARK: - Private methods
    private func getGradientLayer(bounds : CGRect) -> CAGradientLayer{
        let gradient = CAGradientLayer()
        gradient.frame = bounds
        gradient.colors = [startColor.cgColor, midColor.cgColor, endColor.cgColor]
        
        if vertical {
            gradient.startPoint = CGPoint(x: 0.5, y: 0.0)
            gradient.endPoint = CGPoint(x: 0.5, y: 1.0)
        } else {
            gradient.startPoint = CGPoint(x: 0.0, y: 0.5)
            gradient.endPoint = CGPoint(x: 1.0, y: 0.5)
        }
        
        return gradient
    }
    
    private func gradientColor(bounds: CGRect, gradientLayer :CAGradientLayer) -> UIColor? {
        UIGraphicsBeginImageContext(gradientLayer.bounds.size)
        //create UIImage by rendering gradient layer.
        gradientLayer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        //get gradient UIcolor from gradient UIImage
        return UIColor(patternImage: image!)
    }
}

Answer 5

You can add UILabel within UILabel Like this.

class GradientLabel: UILabel {  

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        self.clipsToBounds = true
        DispatchQueue.main.async {
            self.applyGradient(with: Color.gradientColor, gradient: GradientOrientation.topLeftBottomRight)
            self.textColor = UIColor.white
        }
        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.1) {

            let label = UILabel(frame: CGRect(x: 0, y: 0, width: self.frame.size.width, height: self.frame.size.height))
            label.text = self.text
            label.font = self.font
            label.textColor = self.textColor
            label.textAlignment = self.textAlignment
            self.text = ""
            self.addSubview(label)
        }
    }
}

extension UIView {

    func applyGradient(with colours: [UIColor], locations: [NSNumber]? = nil) {
        let gradient = CAGradientLayer()
        gradient.frame = self.bounds
        gradient.colors = colours.map { $0.cgColor }
        gradient.locations = locations
        self.layer.insertSublayer(gradient, at: 0)
    }

    func applyGradient(with colours: [UIColor], gradient orientation: GradientOrientation) {
        let gradient = CAGradientLayer()
        gradient.frame = self.bounds
        gradient.colors = colours.map { $0.cgColor }
        gradient.startPoint = orientation.startPoint
        gradient.endPoint = orientation.endPoint
        self.layer.insertSublayer(gradient, at: 0)
    }
}

Answer 6

I think you can create a gradient color by adjusting the alpha value in the above code.

gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor whiteColor] CGColor],(id)[[UIColor colorWithRed:255/255.0 green:239/255.0 blue:215/255.0 alpha:0.1] CGColor],nil];

I was able to get a gradient effect by doing so.