Feature/cm 965 add image asset protocol

Sources/YCoreUI/Protocols/ImageAsset.swift

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+//
+//  ImageAsset.swift
+//  YCoreUI
+//
+//  Created by Dev Karan on 19/12/22.
+//  Copyright © 2022 Y Media Labs. All rights reserved.
+//
+
+import Foundation
+import UIKit
+
+/// Any named image asset can be loaded from an asset catalog.
+///
+/// All properties and functions have default implementations. At a minimum just have your string-based enum conform
+///  to `ImageAsset` (and have an asset catalog with matching assets). If your enum and assets live inside a Swift
+///  package, override `bundle` to return `.module`. If your assets are categorized within their asset catalog by
+///  a namespace, then override `namespace` to return the proper string prefix.
+public protocol ImageAsset: RawRepresentable where RawValue == String {
+    /// The bundle containing the image assets for this enum (default is `.main`)
+    static var bundle: Bundle { get }
+
+    /// Optional namespace for the image assets (default is `nil`).
+    static var namespace: String? { get }
+
+    /// Fallback image to use in case an image asset cannot be loaded.
+    /// (default is a 16 x 16 square filled with `.systemPink`)
+    static var fallbackImage: UIImage { get }
+
+    /// An image asset for this name value.
+    ///
+    /// Default implementation calls `loadImage` and nil-coalesces to `fallbackImage`.
+    var image: UIImage { get }
+
+    /// Loads the image.
+    ///
+    /// - Returns: The named image or else `nil` if the named asset cannot be loaded.
+    func loadImage() -> UIImage?
+}
+
+extension ImageAsset {
+    /// The bundle containing the image assets for this enum (default is `.main`)
+    public static var bundle: Bundle { .main }
+
+    /// Optional namespace for the image assets (default is `nil`)
+    public static var namespace: String? { nil }
+
+    /// Fallback image to use in case an image asset cannot be loaded.
+    /// (default is a 16 x 16 square filled with `.systemPink`)
+    public static var fallbackImage: UIImage {
+        let renderer = UIGraphicsImageRenderer(size: CGSize(width: 16, height: 16))
+        let image = renderer.image { ctx in
+            UIColor.systemPink.setFill()
+            ctx.fill(CGRect(origin: .zero, size: renderer.format.bounds.size))
+        }
+        return image
+    }
+
+    /// Loads the named image.
+    ///
+    /// Default implementation uses `UIImage(named:in:compatibleWith:)` passing in the associated `namespace`
+    /// (prepended to `rawValue`) and `bundle`.
+    /// - Returns: The named image or else `nil` if the named asset cannot be loaded.
+    public func loadImage() -> UIImage? {
+        let name: String
+        if let validNamespace = Self.namespace {
+            name = "\(validNamespace)/\(rawValue)"
+        } else {
+            name = rawValue
+        }
+        return UIImage(named: name, in: Self.bundle, compatibleWith: nil)
+    }
+
+    /// An image asset for this name value.
+    ///
+    /// Default implementation calls `loadImage` and nil-coalesces to `fallbackImage`.
+    public var image: UIImage { loadImage() ?? Self.fallbackImage }
+}

Tests/YCoreUITests/Assets/Images.xcassets/Contents.json

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+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Tests/YCoreUITests/Assets/Images.xcassets/Icons/Contents.json

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+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  },
+  "properties" : {
+    "provides-namespace" : true
+  }
+}

Tests/YCoreUITests/Assets/Images.xcassets/Icons/minus.imageset/Contents.json

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+{
+  "images" : [
+    {
+      "filename" : "minus.png",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Tests/YCoreUITests/Assets/Images.xcassets/Icons/plus.imageset/Contents.json

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+{
+  "images" : [
+    {
+      "filename" : "plus.png",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Tests/YCoreUITests/Assets/Images.xcassets/flag_br.imageset/Contents.json

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+{
+  "images" : [
+    {
+      "filename" : "flag_br.png",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Tests/YCoreUITests/Assets/Images.xcassets/flag_ch.imageset/Contents.json

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+{
+  "images" : [
+    {
+      "filename" : "flag_ch.png",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Tests/YCoreUITests/Assets/Images.xcassets/flag_in.imageset/Contents.json

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+{
+  "images" : [
+    {
+      "filename" : "flag_in.png",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Tests/YCoreUITests/Assets/Images.xcassets/flag_us.imageset/Contents.json

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+{
+  "images" : [
+    {
+      "filename" : "flag_us.png",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Tests/YCoreUITests/Protocols/ImageAssetTests.swift

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+//
+//  ImageAssetTests.swift
+//  YCoreUI
+//
+//  Created by Dev Karan on 21/12/22.
+//  Copyright © 2022 Y Media Labs. All rights reserved.
+//
+
+import XCTest
+import YCoreUI
+
+final class ImageAssetTests: XCTestCase {
+    func test_bundle() {
+        XCTAssertEqual(Flags.bundle, .module)
+        XCTAssertEqual(Icons.bundle, .module)
+        XCTAssertEqual(Missing.bundle, .main)
+    }
+
+    func test_namespace() {
+        XCTAssertNil(Flags.namespace)
+        XCTAssertEqual(Icons.namespace, "Icons")
+        XCTAssertNil(Missing.namespace)
+    }
+
+    func test_fallbackImage() {
+        XCTAssertNotNil(Flags.fallbackImage)
+        XCTAssertNotNil(Icons.fallbackImage)
+        XCTAssertEqual(Missing.fallbackImage, UIImage(systemName: "x.squareroot"))
+    }
+
+    func test_loadImageWithNameSpace() {
+        Icons.allCases.forEach {
+            XCTAssertNotNil($0.loadImage())
+        }
+    }
+
+    func test_loadImageWithoutNameSpace() {
+        Flags.allCases.forEach {
+            XCTAssertNotNil($0.loadImage())
+        }
+    }
+
+    func test_missingImage() {
+        Missing.allCases.forEach {
+            XCTAssertNil($0.loadImage())
+            XCTAssertEqual($0.image, UIImage(systemName: "x.squareroot"))
+        }
+    }
+
+    func test_imageAsset_defaultValues() {
+        XCTAssertEqual(DefaultImageAssets.bundle, .main)
+        XCTAssertEqual(DefaultImageAssets.defaultCase.image.pngData(), DefaultImageAssets.fallbackImage.pngData())
+        XCTAssertNil(DefaultImageAssets.namespace)
+    }
+}
+
+enum DefaultImageAssets: String, CaseIterable, ImageAsset {
+    case defaultCase
+}
+
+extension ImageAssetTests {
+    enum Flags: String, CaseIterable, ImageAsset {
+        case unitedStates = "flag_us"
+        case india = "flag_in"
+        case brazil = "flag_br"
+        case switzerland = "flag_ch"
+
+        static var bundle: Bundle { .module }
+    }
+
+    enum Icons: String, CaseIterable, ImageAsset {
+        case plus
+        case minus
+
+        static var bundle: Bundle { .module }
+        static var namespace: String? { "Icons" }
+    }
+
+    enum Missing: String, CaseIterable, ImageAsset {
+        case notHere
+        case gone
+
+        static var fallbackImage: UIImage {
+            let image: UIImage! = UIImage(systemName: "x.squareroot")
+            return image
+        }
+    }
+}