[Issue-50] Support scalable system image. (#57)

* [CM-1245] Support scalable system image.

* Fix tvOS compile error. Minor cleanup.

* Update README

---------

Co-authored-by: Mark Pospesel <[email protected]>

Author: devkaranCT

README.md

@@ -271,8 +271,9 @@ Easily load system images (SF Symbols) from any string-based `Enum`. All you nee
 
 Why bother doing this when it just wraps `UIImage(systemName:)`? Because
 1. `UIImage(systemName:)` returns `UIImage?` while `SystemImage.image` returns `UIImage`.
-2. Organizing your system images into enums encourages better architecture (and helps avoid stringly-typed errors).
-3. Easier to unit test.
+2. By default `SystemImage.image` returns images that scale with Dynamic Type.
+3. Organizing your system images into enums encourages better architecture (and helps avoid stringly-typed errors).
+4. Easier to unit test.
 
 ```swift
 // Conform your Enum to SystemImage

Sources/YCoreUI/Protocols/SystemImage.swift

@@ -21,13 +21,37 @@ public protocol SystemImage: RawRepresentable where RawValue == String {
     ///
     /// Default implementation calls `loadImage` and nil-coalesces to `fallbackImage`.
     var image: UIImage { get }
+    
+    /// Image will scale according to the specified text style.
+    ///
+    /// Default implementation is `.body`.
+    static var textStyle: UIFont.TextStyle? { get }
+    
+    /// Image configuration to be used in `loadImage()`.
+    ///
+    /// Default implementation is `UIImage.SymbolConfiguration(textStyle: textStyle)`.
+    /// Returns `nil` when `textStyle` is `nil`.
+    static var configuration: UIImage.Configuration? { get }
 
     /// Loads the named system image.
     /// - Returns: The named system image or else `nil` if the system image cannot be loaded.
     func loadImage() -> UIImage?
 }
 
 extension SystemImage {
+    /// Image will scale according to the specified text style.
+    public static var textStyle: UIFont.TextStyle? { .body }
+    
+    /// Image configuration to be used in `loadImage()`.
+    ///
+    /// Returns `nil` when `textStyle` is `nil`.
+    public static var configuration: UIImage.Configuration? {
+        guard let textStyle = textStyle else {
+            return nil
+        }
+        return UIImage.SymbolConfiguration(textStyle: textStyle)
+    }
+    
     /// Fallback image to use in case a system image cannot be loaded.
     /// (default is a 16 x 16 square filled with `.systemPink`)
     public static var fallbackImage: UIImage {
@@ -44,7 +68,7 @@ extension SystemImage {
     /// Default implementation uses `UIImage(systemName:)` passing in the associated `rawValue`.
     /// - Returns: The named system image or else `nil` if the system image cannot be loaded.
     public func loadImage() -> UIImage? {
-        UIImage(systemName: rawValue)
+        UIImage(systemName: rawValue, withConfiguration: Self.configuration)
     }
 
     /// A system image for this name value.

Tests/YCoreUITests/Protocols/SystemImageTests.swift

@@ -32,7 +32,22 @@ final class SystemImageTests: XCTestCase {
 
         YCoreUI.isLoggingEnabled = true
     }
-
+    
+    func test_defaultImageScaling() {
+        XCTAssertEqual(Symbols.textStyle, .body)
+        XCTAssertEqual(Symbols.configuration, UIImage.SymbolConfiguration(textStyle: .body))
+    }
+    
+    func test_imageWithoutScaling() {
+        XCTAssertNil(SymbolWithoutScaling.textStyle)
+        XCTAssertNil(SymbolWithoutScaling.configuration)
+    }
+    
+    func test_customImageScaling() {
+        XCTAssertEqual(SymbolCustomScaling.textStyle, .title1)
+        XCTAssertEqual(SymbolCustomScaling.configuration, UIImage.SymbolConfiguration(textStyle: .title1))
+    }
+    
     func test_systemImage_deliversDefaultFallback() {
         XCTAssertEqual(DefaultSymbols.defaultCase.image.pngData(), DefaultSymbols.fallbackImage.pngData())
     }
@@ -59,4 +74,18 @@ extension SystemImageTests {
     enum DefaultSymbols: String, CaseIterable, SystemImage {
         case defaultCase
     }
+    
+    enum SymbolWithoutScaling: String, CaseIterable, SystemImage {
+        case checked = "checkmark.square"
+        case unchecked = "square"
+
+        static var textStyle: UIFont.TextStyle? { nil }
+    }
+    
+    enum SymbolCustomScaling: String, CaseIterable, SystemImage {
+        case checked = "checkmark.square"
+        case unchecked = "square"
+
+        static var textStyle: UIFont.TextStyle? { .title1 }
+    }
 }