DesignKit: Add Fonts protocol.

DesignKit/Source/Fonts.swift

@@ -0,0 +1,46 @@
+// 
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import UIKit
+
+/// Describe Fonts
+@objc public protocol Fonts {
+    
+    /// Returns an instance of the font associated with the text style and scaled appropriately for the content size category defined in the trait collection.
+    func font(forTextStyle textStyle: UIFont.TextStyle, compatibleWith traitCollection: UITraitCollection?) -> UIFont
+
+    // MARK: - TextStyle shortcuts
+    
+    var largeTitle: UIFont { get }
+    var title1: UIFont { get }
+    var title2: UIFont { get }
+    var title3: UIFont { get }
+    var headline: UIFont { get }
+    var subheadline: UIFont { get }
+    var body: UIFont { get }
+    var callout: UIFont { get }
+    var caption1: UIFont { get }
+    var caption2: UIFont { get }
+}
+
+// MARK: - Default implementation
+extension Fonts {
+    
+    /// Returns an instance of the font associated with the text style and scaled appropriately for the user's selected content size category.
+    func font(forTextStyle textStyle: UIFont.TextStyle) -> UIFont {
+        return self.font(forTextStyle: textStyle, compatibleWith: nil)
+    }
+}

DesignKit/Source/ThemeV2.swift

@@ -23,6 +23,9 @@ import UIKit
     /// Colors object
     var colors: Colors { get }
     
+    /// Fonts object
+    var fonts: Fonts { get }
+    
     /// may contain more design components in future, like icons, audio files etc.
     
 }