Simple swift color picker popover (iOS)

Question

Is there is a simple way to implement a color picker popover in swift? Are there any built-in libraries or UI elements that I could leverage for this purpose? I saw some c

Answer 1

using Michael Ros answer,

If you want to use this view by objective-c viewcontroller you can simply create a new swift file called ColorPickerView and add a uiview to your viewcontroller on the storyboard and select ColorPickerView as it's class name. then make your view controller a notification observer of name @"colorIsPicked"

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(updateColor) name:@"colorIsPicked" object:nil];

Code for ColorPickerView.swift

class ColorPickerView : UIView {

@objc public lazy var onColorDidChange: ((_ color: UIColor) -> ()) = {
           
    //send a notification for the caller view to update its elements if necessery
    NotificationCenter.default.post(name: Notification.Name("colorIsPicked"), object: nil)

}


let saturationExponentTop:Float = 2.0
let saturationExponentBottom:Float = 1.3

let grayPaletteHeightFactor: CGFloat = 0.1
var rect_grayPalette = CGRect.zero
var rect_mainPalette = CGRect.zero

// adjustable
var elementSize: CGFloat = 10.0 {
    didSet {
        setNeedsDisplay()
    }
}

override init(frame: CGRect) {
    super.init(frame: frame)
    setup()
}

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

private func setup() {
    
    self.clipsToBounds = true
    let touchGesture = UILongPressGestureRecognizer(target: self, action: #selector(self.touchedColor(gestureRecognizer:)))
    touchGesture.minimumPressDuration = 0
    touchGesture.allowableMovement = CGFloat.greatestFiniteMagnitude
    self.addGestureRecognizer(touchGesture)
}



override func draw(_ rect: CGRect) {
    let context = UIGraphicsGetCurrentContext()
    
    rect_grayPalette = CGRect(x: 0, y: 0, width: rect.width, height: rect.height * grayPaletteHeightFactor)
    rect_mainPalette = CGRect(x: 0, y: rect_grayPalette.maxY,
                              width: rect.width, height: rect.height - rect_grayPalette.height)
    
    // gray palette
    for y in stride(from: CGFloat(0), to: rect_grayPalette.height, by: elementSize) {
        
        for x in stride(from: (0 as CGFloat), to: rect_grayPalette.width, by: elementSize) {
            let hue = x / rect_grayPalette.width
            
            let color = UIColor(white: hue, alpha: 1.0)
            
            context!.setFillColor(color.cgColor)
            context!.fill(CGRect(x:x, y:y, width:elementSize, height:elementSize))
        }
    }
    
    // main palette
    for y in stride(from: CGFloat(0), to: rect_mainPalette.height, by: elementSize) {
        
        var saturation = y < rect_mainPalette.height / 2.0 ? CGFloat(2 * y) / rect_mainPalette.height : 2.0 * CGFloat(rect_mainPalette.height - y) / rect_mainPalette.height
        saturation = CGFloat(powf(Float(saturation), y < rect_mainPalette.height / 2.0 ? saturationExponentTop : saturationExponentBottom))
        let brightness = y < rect_mainPalette.height / 2.0 ? CGFloat(1.0) : 2.0 * CGFloat(rect_mainPalette.height - y) / rect_mainPalette.height
        
        for x in stride(from: (0 as CGFloat), to: rect_mainPalette.width, by: elementSize) {
            let hue = x / rect_mainPalette.width
            
            let color = UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: 1.0)
            
            context!.setFillColor(color.cgColor)
            context!.fill(CGRect(x:x, y: y + rect_mainPalette.origin.y,
                                 width: elementSize, height: elementSize))
        }
    }
}



func getColorAtPoint(point: CGPoint) -> UIColor
{
    var roundedPoint = CGPoint(x:elementSize * CGFloat(Int(point.x / elementSize)),
                               y:elementSize * CGFloat(Int(point.y / elementSize)))
    
    let hue = roundedPoint.x / self.bounds.width
    
    
    // main palette
    if rect_mainPalette.contains(point)
    {
        // offset point, because rect_mainPalette.origin.y is not 0
        roundedPoint.y -= rect_mainPalette.origin.y
        
        var saturation = roundedPoint.y < rect_mainPalette.height / 2.0 ? CGFloat(2 * roundedPoint.y) / rect_mainPalette.height
            : 2.0 * CGFloat(rect_mainPalette.height - roundedPoint.y) / rect_mainPalette.height
        
        saturation = CGFloat(powf(Float(saturation), roundedPoint.y < rect_mainPalette.height / 2.0 ? saturationExponentTop : saturationExponentBottom))
        let brightness = roundedPoint.y < rect_mainPalette.height / 2.0 ? CGFloat(1.0) : 2.0 * CGFloat(rect_mainPalette.height - roundedPoint.y) / rect_mainPalette.height
        
        return UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: 1.0)
    }
    // gray palette
    else{
        
        return UIColor(white: hue, alpha: 1.0)
    }
}


@objc func touchedColor(gestureRecognizer: UILongPressGestureRecognizer){
    let point = gestureRecognizer.location(in: self)
    let color = getColorAtPoint(point: point)
    
    self.onColorDidChange(color)
}
 }