Explaining the Theme.swift file

Theme.swift

import Foundation
import UIKit

struct Theme {
    
    /// Common padding for use in autolayout code
    static let Padding = 20
    
    /// Common app colors
    struct Color {
        static let White = UIColor(hex: 0xFFFFFF)
        static let Green = UIColor(hex: 0x6EC13A)
        static let Gray = UIColor(hex: 0x666666)
        static let LightGray = UIColor(hex: 0x7F7F7F)
    }
    
    enum Font {
        
        case Light
        case Default
        case Medium
        case Bold
        
        func fontWithSize(size: CGFloat) -> UIFont {
            
            var font: UIFont?
            
            switch (self) {
            case .Light:
                font = UIFont.systemFontOfSize(size, weight: UIFontWeightLight)
            case .Default:
                font = UIFont.systemFontOfSize(size, weight: UIFontWeightRegular)
            case .Medium:
                font = UIFont.systemFontOfSize(size, weight: UIFontWeightMedium)
            case .Bold:
                font = UIFont.systemFontOfSize(size, weight: UIFontWeightBold)
            }
        
            if let font = font {
                return font
            } else {
                print("Font not found")
                return UIFont.systemFontOfSize(size)
            }
        }
    }
    
    /// You can also define MotionEffects that you can add to UIViews in your app
    /// simply by calling `self.titleLabel.addMotionEffect(Theme.MotionEffects.ForegroundMotionEffectGroup)`
    /// Pretty neat!
    struct MotionEffects {
    
        /// Motion effect group to be added to all background elements to ensure consistency
        static let BackgroundMotionEffectGroup: UIMotionEffectGroup = {
            
            let value = -10
            
            let verticalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.y", type: .TiltAlongVerticalAxis)
            verticalMotionEffect.maximumRelativeValue = value
            verticalMotionEffect.minimumRelativeValue = -value
            
            let horizontalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.x", type: .TiltAlongHorizontalAxis)
            horizontalMotionEffect.maximumRelativeValue = value
            horizontalMotionEffect.minimumRelativeValue = -value
            
            let effectGroup = UIMotionEffectGroup()
            effectGroup.motionEffects = [verticalMotionEffect, horizontalMotionEffect]
            
            return effectGroup
        }()
    } 
    
    /// Configure all the UIAppearance Proxies.
    static func applyAppearance() {
    
        let titleTextAttributes = [
            NSForegroundColorAttributeName: Theme.Color.White,
            NSFontAttributeName: Theme.Font.Default.fontWithSize(17)
        ]
        
        UINavigationBar.appearance().titleTextAttributes = titleTextAttributes
    }
}