UIApplication+AppIcon.swift

//
//  UIApplication+AppIcon.swift
//
//  The MIT License (MIT)
//
//  Copyright (c) 2020-present patrick piemonte (http://patrickpiemonte.com/)
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in all
//  copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//  SOFTWARE.
//

import UIKit
import Foundation

extension UIApplication {

    public enum AppIcon: String, CaseIterable, Identifiable {
        case appIcon = "AppIcon"
        case darkMode = "AppIcon-Dark"

        public var id: String { rawValue }
        
        var iconName: String? {
            switch self {
            case .appIcon:
                return nil // reset app icon to initial state
            default:
                return rawValue
            }
        }

        var description: String {
            switch self {
            case .appIcon:
                return "Default"
            case .darkMode:
                return "Dark Mode"
            }
        }

        var preview: UIImage {
            UIImage(named: rawValue + "-Preview") ?? UIImage()
        }
    }

    public enum AppIconError: Error {
        case notSupported
    }

    public var selectedAppIcon: AppIcon {
        guard UIApplication.shared.supportsAlternateIcons else {
            return .appIcon
        }
        let selectedIconName = UIApplication.shared.alternateIconName
        return AppIcon.allCases.first(where: {
            $0.iconName == selectedIconName
        }) ?? .appIcon
    }

    public func setAppIcon(appIcon: UIApplication.AppIcon, completionHandler: ((Swift.Result<String?, Error>) -> Void)?) {
        guard UIApplication.shared.supportsAlternateIcons else {
            DispatchQueue.main.async {
                completionHandler?(.failure(AppIconError.notSupported))
            }
            return
        }

        self.setAlternateIconName(appIcon.iconName) { error in
            if let error = error {
                completionHandler?(.failure(error))
            } else {
                completionHandler?(.success(UIApplication.shared.alternateIconName))
            }
        }
    }

}