Creates an instance of `UIColor`, that generates its color data dynamically based on the current `userInterfaceStyle`. Furthermore this method falls back to the `lightVariant` color for iOS versions prior to iOS 13.

UIColor+MakeDynamicColor.swift

//
//  UIColor+MakeDynamicColor.swift
//
//  Created by Felix Mau on 22/09/19.
//  Copyright © 2019 Felix Mau. All rights reserved.
//

import Foundation

extension UIColor {

  /// Creates a dynamic color that automatically adapts to the current user interface style.
  ///
  /// On iOS 13 and later, the returned color switches between the provided light and dark variants
  /// based on the current `UITraitCollection`. On earlier iOS versions, the light variant is used.
  ///
  /// - Parameters:
  ///   - lightVariant: The color used in light mode and on iOS versions prior to iOS 13.
  ///   - darkVariant: The color used in dark mode.
  ///
  /// - Returns: A `UIColor` that adapts to the current interface style.
  static func makeDynamicColor(lightVariant: UIColor, darkVariant: UIColor) -> UIColor {
    guard #available(iOS 13.0, *) else {
      // Prior to iOS 13 there was no dark-mode, so we`re gonna return the light variant.
      return lightVariant
    }

    return UIColor { traitCollection -> UIColor in
      traitCollection.userInterfaceStyle == .dark
        ? darkVariant
        : lightVariant
    }
  }
}