Objective-c – How to add a gradient tint color to a UISlider in XCode 6

gradientios8objective cuisliderxcode6

I'm working on a design application that has a section for selecting colors by three sliders for RGB.
As we can see in xcode, where we want to select a color by RGB values, the slider tint color is a gradient color that changes when we change the sliders. I want to use this in my application. but I have no idea about how to do this?

I've found this code in a blog. but didn't work for me.

- (void)setGradientToSlider:(UISlider *)Slider WithColors:(NSArray *)Colors{

    UIView * view = (UIView *)[[Slider subviews]objectAtIndex:0];

    UIImageView * maxTrackImageView = (UIImageView *)[[view subviews]objectAtIndex:0];

    CAGradientLayer * maxTrackGradient = [CAGradientLayer layer];
    CGRect rect = maxTrackImageView.frame;
    rect.origin.x = view.frame.origin.x;

    maxTrackGradient.frame = rect;
    maxTrackGradient.colors = Colors;

    [maxTrackGradient setStartPoint:CGPointMake(0.0, 0.5)];
    [maxTrackGradient setEndPoint:CGPointMake(1.0, 0.5)];

    [[maxTrackImageView layer] insertSublayer:maxTrackGradient atIndex:0];

    /////////////////////////////////////////////////////

    UIImageView * minTrackImageView = (UIImageView *)[[view subviews]objectAtIndex:1];

    CAGradientLayer * minTrackGradient = [CAGradientLayer layer];
    rect = minTrackImageView.frame;
    rect.size.width = maxTrackImageView.frame.size.width;
    rect.origin.x = 0;
    rect.origin.y = 0;

    minTrackGradient.frame = rect;
    minTrackGradient.colors = Colors;

    [minTrackGradient setStartPoint:CGPointMake(0.0, 0.5)];
    [minTrackGradient setEndPoint:CGPointMake(1.0, 0.5)];

    [minTrackImageView.layer insertSublayer:minTrackGradient atIndex:0];

}

I would appreciate any helps. Thanks.

Best Answer

While it didnt give me the desired results here is a down and dirty Swift version of the answer above for those that want to try it.

func setSlider(slider:UISlider) {

    let tgl = CAGradientLayer()
    let frame = CGRectMake(0, 0, slider.frame.size.width, 5)
    tgl.frame = frame
    tgl.colors = [UIColor.blueColor().CGColor, UIColor.greenColor().CGColor, UIColor.yellowColor().CGColor, UIColor.orangeColor().CGColor, UIColor.redColor().CGColor]
    tgl.startPoint = CGPointMake(0.0, 0.5)
    tgl.endPoint = CGPointMake(1.0, 0.5)

    UIGraphicsBeginImageContextWithOptions(tgl.frame.size, tgl.opaque, 0.0);
    tgl.renderInContext(UIGraphicsGetCurrentContext()!)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    image.resizableImageWithCapInsets(UIEdgeInsetsZero)

    slider.setMinimumTrackImage(image, forState: .Normal)
    //slider.setMaximumTrackImage(image, forState: .Normal)

}

UPDATE for Swift 4.0

func setSlider(slider:UISlider) {
    let tgl = CAGradientLayer()
    let frame = CGRect.init(x:0, y:0, width:slider.frame.size.width, height:5)
    tgl.frame = frame
    tgl.colors = [UIColor.blue.cgColor, UIColor.green.cgColor, UIColor.yellow.cgColor, UIColor.orange.cgColor, UIColor.red.cgColor]
    tgl.startPoint = CGPoint.init(x:0.0, y:0.5)
    tgl.endPoint = CGPoint.init(x:1.0, y:0.5)

    UIGraphicsBeginImageContextWithOptions(tgl.frame.size, tgl.isOpaque, 0.0);
    tgl.render(in: UIGraphicsGetCurrentContext()!)
    if let image = UIGraphicsGetImageFromCurrentImageContext() {
        UIGraphicsEndImageContext()

        image.resizableImage(withCapInsets: UIEdgeInsets.zero)

        slider.setMinimumTrackImage(image, for: .normal)
    }
}
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