RomanEsin

import Foundation
import GameController

protocol ControllerAnimatable: class {
    var controller: GCController { get }
}

extension ControllerAnimatable {
    /// Animates controller light color to a specified color of `GCColor` type.
    /// - Parameters:

RomanEsin

// color - source color, which is must be replaced
// withColor - target color
// tolerance - value in range from 0 to 1
func replaceColor(color: UIColor, withColor: UIColor, image: UIImage, tolerance: CGFloat) -> UIImage {

    // This function expects to get source color(color which is supposed to be replaced)
    // and target color in RGBA color space, hence we expect to get 4 color components: r, g, b, a
    assert(color.cgColor.numberOfComponents == 4 && withColor.cgColor.numberOfComponents == 4,
           "Must be RGBA colorspace")

RomanEsin

// In your preview struct just add
// `darkThemePreview()` to the view you're previewing!

import SwiftUI

extension View {
    func darkThemePreview() -> some View {
        Group {
            self
            self