Initial implementation

Package.swift

@@ -1,28 +1,15 @@
-// swift-tools-version: 5.6
-// The swift-tools-version declares the minimum version of Swift required to build this package.
+// swift-tools-version:5.1
 
 import PackageDescription
 
 let package = Package(
     name: "AttributedFont",
+    platforms: [.iOS(.v13), .macOS(.v10_15), .tvOS(.v13), .watchOS(.v6)],
     products: [
-        // Products define the executables and libraries a package produces, and make them visible to other packages.
-        .library(
-            name: "AttributedFont",
-            targets: ["AttributedFont"]),
-    ],
-    dependencies: [
-        // Dependencies declare other packages that this package depends on.
-        // .package(url: /* package url */, from: "1.0.0"),
+        .library(name: "AttributedFont", targets: ["AttributedFont", "Previews"])
     ],
     targets: [
-        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
-        // Targets can depend on other targets in this package, and on products in packages this package depends on.
-        .target(
-            name: "AttributedFont",
-            dependencies: []),
-        .testTarget(
-            name: "AttributedFontTests",
-            dependencies: ["AttributedFont"]),
+        .target(name: "AttributedFont", dependencies: []),
+        .target(name: "Previews", dependencies: ["AttributedFont"])
     ]
 )

Sources/AttributedFont/AttributedFont+Font.swift

@@ -0,0 +1,74 @@
+import SwiftUI
+
+// MARK: Creating Custom Fonts
+
+@available(iOS 13.0, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+extension AttributedFont {
+
+    @available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *)
+    public static func custom(_ name: String, fixedSize: CGFloat, attributes: Attributes) -> Self {
+        return .init(name: name, fixedSize: fixedSize, attributes: attributes)
+    }
+}
+
+// MARK: Styling a Font
+
+@available(iOS 13.0, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+extension AttributedFont {
+
+    public func italic() -> Self {
+        var modified = self
+        modified.font = modified.font.italic()
+        return modified
+    }
+
+    public func smallCaps() -> Self {
+        var modified = self
+        modified.font = modified.font.smallCaps()
+        return modified
+    }
+
+    public func lowercaseSmallCaps() -> Self {
+        var modified = self
+        modified.font = modified.font.lowercaseSmallCaps()
+        return modified
+    }
+
+    public func uppercaseSmallCaps() -> Self {
+        var modified = self
+        modified.font = modified.font.uppercaseSmallCaps()
+        return modified
+    }
+
+    public func monospacedDigit() -> Self {
+        var modified = self
+        modified.font = modified.font.monospacedDigit()
+        return modified
+    }
+
+    public func weight(_ weight: Font.Weight) -> Self {
+        var modified = self
+        modified.font = modified.font.weight(weight)
+        return modified
+    }
+
+    public func bold() -> Self {
+        var modified = self
+        modified.font = modified.font.bold()
+        return modified
+    }
+
+    @available(iOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0, *)
+    public func monospaced() -> Self {
+        var modified = self
+        modified.font = modified.font.monospaced()
+        return modified
+    }
+
+    @available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *)
+    public func leading(_ leading: Font.Leading) -> Self {
+        var modified = self
+        modified.font = modified.font.leading(leading)
+        return modified
+    }
+}

Sources/AttributedFont/AttributedFont.swift

@@ -1,6 +1,57 @@
-public struct AttributedFont {
-    public private(set) var text = "Hello, World!"
+import SwiftUI
 
-    public init() {
+@available(iOS 13.0, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+public struct AttributedFont: Hashable {
+
+    public internal(set) var name: String
+    public internal(set) var size: CGFloat
+    public internal(set) var attributes: Attributes
+
+    public internal(set) var font: Font
+    public internal(set) var ctFont: CTFont
+
+    @available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *)
+    internal init(name: String, fixedSize: CGFloat, attributes: Attributes) {
+        self.name = name
+        self.size = fixedSize
+        self.attributes = attributes
+
+        self.font = .custom(name, fixedSize: fixedSize)
+        self.ctFont = CTFontCreateWithName(name as CFString, size, nil)
+    }
+}
+
+@available(iOS 13.0, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+extension AttributedFont {
+
+    public struct Attributes: Hashable {
+
+        public internal(set) var kerning: CGFloat?
+        public internal(set) var tracking: CGFloat?
+        public internal(set) var lineHeightMultiple: CGFloat?
+
+        public init(kerning: CGFloat? = nil, tracking: CGFloat? = nil, lineHeightMultiple: CGFloat? = nil) {
+            self.kerning = kerning
+            self.tracking = tracking
+            self.lineHeightMultiple = lineHeightMultiple
+        }
+    }
+}
+
+
+@available(iOS 13.0, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+extension AttributedFont {
+
+    public var lineSpacing: CGFloat? {
+        guard let lineHeightMultiple = attributes.lineHeightMultiple else {
+            return nil
+        }
+        let originalLineHeight = CTFontGetLineHeight(ctFont)
+        let customLineHeight = originalLineHeight * lineHeightMultiple
+        guard customLineHeight > originalLineHeight else {
+            return nil
+        }
+        let lineSpacing = customLineHeight - originalLineHeight
+        return lineSpacing
     }
 }