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.
This is a really effective approach that I've found after a lot of web search. So it's better to share it here as a complete answer. The following code is a Swift Class
That you can use to create and use gradients as UIView
or UIImage
.
import Foundation
import UIKit
class Gradient: UIView{
// Gradient Color Array
private var Colors: [UIColor] = []
// Start And End Points Of Linear Gradient
private var SP: CGPoint = CGPoint.zeroPoint
private var EP: CGPoint = CGPoint.zeroPoint
// Start And End Center Of Radial Gradient
private var SC: CGPoint = CGPoint.zeroPoint
private var EC: CGPoint = CGPoint.zeroPoint
// Start And End Radius Of Radial Gradient
private var SR: CGFloat = 0.0
private var ER: CGFloat = 0.0
// Flag To Specify If The Gradient Is Radial Or Linear
private var flag: Bool = false
// Some Overrided Init Methods
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override init(frame: CGRect) {
super.init(frame: frame)
}
// Draw Rect Method To Draw The Graphics On The Context
override func drawRect(rect: CGRect) {
// Get Context
let context = UIGraphicsGetCurrentContext()
// Get Color Space
let colorSpace = CGColorSpaceCreateDeviceRGB()
// Create Arrays To Convert The UIColor to CG Color
var colorComponent: [CGColor] = []
var colorLocations: [CGFloat] = []
var i: CGFloat = 0.0
// Add Colors Into The Color Components And Use An Index Variable For Their Location In The Array [The Location Is From 0.0 To 1.0]
for color in Colors {
colorComponent.append(color.CGColor)
colorLocations.append(i)
i += CGFloat(1.0) / CGFloat(self.Colors.count - 1)
}
// Create The Gradient With The Colors And Locations
let gradient: CGGradientRef = CGGradientCreateWithColors(colorSpace, colorComponent, colorLocations)
// Create The Suitable Gradient Based On Desired Type
if flag {
CGContextDrawRadialGradient(context, gradient, SC, SR, EC, ER, 0)
} else {
CGContextDrawLinearGradient(context, gradient, SP, EP, 0)
}
}
// Get The Input Data For Linear Gradient
func CreateLinearGradient(startPoint: CGPoint, endPoint: CGPoint, colors: UIColor...) {
self.Colors = colors
self.SP = startPoint
self.EP = endPoint
self.flag = false
}
// Get The Input Data For Radial Gradient
func CreateRadialGradient(startCenter: CGPoint, startRadius: CGFloat, endCenter: CGPoint, endRadius: CGFloat, colors: UIColor...) {
self.Colors = colors
self.SC = startCenter
self.EC = endCenter
self.SR = startRadius
self.ER = endRadius
self.flag = true
}
// Function To Convert Gradient To UIImage And Return It
func getImage() -> UIImage {
// Begin Image Context
UIGraphicsBeginImageContext(self.bounds.size)
// Draw The Gradient
self.drawRect(self.frame)
// Get Image From The Current Context
let image = UIGraphicsGetImageFromCurrentImageContext()
// End Image Context
UIGraphicsEndImageContext()
// Return The Result Gradient As UIImage
return image
}
}