Make UIColor darker(-0.1) or lighter(0.5). For example, let color = color.shadeColor(factor: 0.35) // makes color lighter

UIColor+ColorShade.swift

import UIKit

extension UIColor {
    func shadeColor(factor: CGFloat) -> UIColor {
        var r: CGFloat = 0
        var g: CGFloat = 0
        var b: CGFloat = 0
        var a: CGFloat = 0
        
        let t: CGFloat = factor < 0 ? 0 : 1
        let p: CGFloat = factor < 0 ? -factor : factor
        
        getRed(&r, green: &g, blue: &b, alpha: &a)
        r = (t - r) * p + r
        g = (t - g) * p + g
        b = (t - b) * p + b
        
        return UIColor(red: r, green: g, blue: b, alpha: a)
    }
}