Implement dialpad view controller

Riot/Modules/Call/Dialpad/Views/DialpadButton.swift

@@ -0,0 +1,56 @@
+// 
+// Copyright 2020 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
+
+/// Digit button class for Dialpad screen
+class DialpadButton: UIButton {
+    
+    private enum Constants {
+        static let size: CGSize = CGSize(width: 68, height: 68)
+    }
+    
+    init() {
+        super.init(frame: CGRect(origin: .zero, size: Constants.size))
+    }
+    
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        setup()
+    }
+    
+    required init?(coder: NSCoder) {
+        super.init(coder: coder)
+        setup()
+    }
+    
+    private func setup() {
+        clipsToBounds = true
+        layer.cornerRadius = Constants.size.width/2
+    }
+    
+}
+
+//  MARK: - Themable
+
+extension DialpadButton: Themable {
+    
+    func update(theme: Theme) {
+        setTitleColor(theme.textPrimaryColor, for: .normal)
+        backgroundColor = theme.headerBackgroundColor
+    }
+    
+}