Color wheel or color picker in iOS

Question

How can I make a color wheel, color picker, or hue selector in iOS for use on the iPad.

Here is an example picture of a color picker similar to what I want.

Answer 1

I did create a sector of a color wheel in draw(_ rect: CGRect). See here.

That my color wheel:

This view based on the next lines of code:

override func draw(_ rect: CGRect) {
    guard let context = UIGraphicsGetCurrentContext() else {
        return
    }

    // Choice width and x position of a rect where will be placed you picker
    for x in stride(from: bounds.midX - bounds.height, to: bounds.midX + bounds.height, by: elementSize) {

        // Choice height and y position of the rect
        for y in stride(from: 0, to: rect.height, by: elementSize) {

            // Select color for a point
            context.setFillColor(colorFor(x: x, y: y))

            // Select color for the point with elementSize which we declare and init as class property
            context.fill(CGRect(x: x, y: y, width: elementSize, height: elementSize))
        }
    }
}