krummler

import UIKit

// MARK: Image helpers

extension UIImage {
    struct Constants {
        static let defaultTraits = [UITraitCollection(userInterfaceStyle: .dark),
                                    UITraitCollection(userInterfaceStyle: .light)]
    }

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combinedImages.imageAsset?.image(with: UITraitCollection(userInterfaceStyle: .light))
combinedImages.imageAsset?.image(with: UITraitCollection(userInterfaceStyle: .dark))

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// Create an asset
let set = UIImageAsset()

// Define traits to be specific for the images
let darkTraits = UITraitCollection(traitsFrom: [UITraitCollection(userInterfaceStyle: .dark),
                                                UITraitCollection(displayScale: someDarkImage.scale)])
let lightTraits = UITraitCollection(traitsFrom: [UITraitCollection(userInterfaceStyle: .light),
                                                 UITraitCollection(displayScale: someLightImage.scale)])

// Register the images alongside the traits

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let someImage = UIImage.buttonBackground(color: backgroundColor,
                                         borderColor: borderColour,
                                         borderWidth: 2,
                                         cornerRadius: 8)

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extension UIImage {
    static func buttonBackground(color: UIColor,
                                         borderColor: UIColor,
                                         borderWidth: CGFloat,
                                         cornerRadius: CGFloat) -> UIImage {
        let width = max(2, cornerRadius * 2)
        let size = CGSize(width: width, height: width)

        return UIGraphicsImageRenderer(size: size).image { context in
            color.setFill()

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let backgroundColor = UIColor {
    $0.userInterfaceStyle == .dark ?
        UIColor(red: 10.0 / 255, green: 40.0 / 255, blue: 58.0 / 255, alpha: 1) :
        UIColor(red: 183.0 / 255, green: 228.0 / 255, blue: 255.0 / 255, alpha: 1)
}

// Or in short:
let borderColour = UIColor {
    $0.userInterfaceStyle == .dark ?
        UIColor(red: 197.0 / 255, green: 197.0 / 255, blue: 197.0 / 255, alpha: 1) :

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extension UIButton {
    func apply(style: ButtonStyle) {
        backgroundColor = nil

        titleLabel?.font = style.font
        contentEdgeInsets = style.insets

        setTitleColor(style.enabled.foreground, for: .normal)
        setTitleColor(style.highlighted.foreground, for: .highlighted)
        setTitleColor(style.disabled.foreground, for: .disabled)

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private struct Palette {
    static let foreground = UIColor(named: "color/foreground")!
}

struct ComponentStyle {
    struct Button {
        private static let defaultInsets = UIEdgeInsets(top: 12, left: 16, bottom: 12, right: 16)
        private static let defaultFont = UIFont.preferredFont(forTextStyle: .body)

        static let primary =

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// Note: Idealy, these are generated using SwiftGen
private struct Palette {
    static let foreground = UIColor(named: "color/foreground")!
}

private struct Fonts {
    static let body = UIFont.preferredFont(forTextStyle: .body)
}

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extension ButtonStyle {
    func apply(to button: UIButton) {
        button.backgroundColor = nil

        button.titleLabel?.font = font
        button.contentEdgeInsets = insets

        button.setTitleColor(enabled.foreground, for: .normal)
        button.setTitleColor(highlighted.foreground, for: .highlighted)
        button.setTitleColor(disabled.foreground, for: .disabled)