         }
     }
     
-    public struct DevicePortraitSize {
+    public class DevicePortraitSize {
         public static let phone4 = CGSize(width: 320, height: 480) // @2x:  640 x  960
         public static let phone5 = CGSize(width: 320, height: 568) // @2x:  640 x 1136
         public static let phone6 = CGSize(width: 375, height: 667) // @2x:  750 x 1334

        public static let padPro = CGSize(width: 1024, height: 1366) // @2x: 2048 x 2732
    }
    
    public struct DesignPortraitWidth {
        public static var phone = DevicePortraitSize.phone6.width
        public static var pad = DevicePortraitSize.pad.width
        public static var universal = DevicePortraitSize.pad.width

import UIKit

public class Screen: NSObject {
    public class Height {
        public static let statusBar: CGFloat = 20
        public static let navigationBar: CGFloat = 44
        public static let tabBar: CGFloat  = 49
