Swift helper for compatibility

Swift4Compat.swift

//
//  Swift4Compat.swift
//  openrider
//
//  Created by Jeremie Girault on 14/06/2017.
//  Copyright © 2017 EC1. All rights reserved.
//

import UIKit

#if swift(>=4)

    extension UILayoutPriority: ExpressibleByFloatLiteral, ExpressibleByIntegerLiteral {
        public init(floatLiteral value: Float) { self.init(rawValue: value) }

        public init(integerLiteral value: Int) { self.init(rawValue: Float(value)) }

        public static func + (lhs: UILayoutPriority, rhs: UILayoutPriority) -> UILayoutPriority {
            return UILayoutPriority(rawValue: lhs.rawValue + rhs.rawValue)
        }

        public static func - (lhs: UILayoutPriority, rhs: UILayoutPriority) -> UILayoutPriority {
            return UILayoutPriority(rawValue: lhs.rawValue - rhs.rawValue)
        }
    }

#else

    extension UILayoutPriority {
        public static let required = UILayoutPriorityRequired
        public static let defaultHigh = UILayoutPriorityDefaultHigh
        public static let defaultLow = UILayoutPriorityDefaultLow

        public static let fittingSizeLevel = UILayoutPriorityFittingSizeLevel
    }

    public struct NSAttributedStringKey: RawRepresentable, Hashable {
        public let rawValue: String
        public init(rawValue: String) { self.rawValue = rawValue }
        public init(_ rawValue: String) { self.rawValue = rawValue }

        public static func == (lhs: NSAttributedStringKey, rhs: NSAttributedStringKey) -> Bool { return rhs.rawValue == lhs.rawValue }
        public var hashValue: Int { return rawValue.hashValue }
    }

    extension NSAttributedStringKey {
        public static let font = NSAttributedStringKey(NSFontAttributeName)
        public static let foregroundColor = NSAttributedStringKey(NSForegroundColorAttributeName)
    }

    fileprivate extension Dictionary where Key == NSAttributedStringKey, Value == Any {
        var compatDictionary: [String: Any] {
            var dic = [String: Any]()
            for (key, value) in self {
                dic[key.rawValue] = value
            }
            return dic
        }
    }

    extension NSAttributedString {

        public func enumerateAttribute(_ attrName: NSAttributedStringKey,
                                       in enumerationRange: NSRange,
                                       options opts: NSAttributedString.EnumerationOptions = [],
                                       using block: (Any?, NSRange, UnsafeMutablePointer<ObjCBool>) -> Void) {
            enumerateAttribute(attrName.rawValue, in: enumerationRange, options: opts, using: block)
        }

        public convenience init(string: String, attributes: [NSAttributedStringKey: Any]) {
            self.init(string: string, attributes: attributes.compatDictionary)
        }
    }

    extension NSMutableAttributedString {
        public func addAttributes(_ attributes: [NSAttributedStringKey: Any], range: NSRange) {
            addAttributes(attributes.compatDictionary, range: range)
        }
    }

#endif