Swift Dictionary extensions to return all keys for a value, et al.

DictionaryExtensions.swift

//
//  DictionaryExtensions.swift
//  
//
//  Created by Tommie N. Carter, Jr., MBA on 12/14/15.
//  Copyright © 2015 MING Technology. All rights reserved.
//

import Foundation



extension Dictionary where Value : Equatable {
//    func allKeysForValue<K, V : Equatable>(dict: [K : V], val: V) -> [K] {
//        return dict.filter{ $0.1 == val }.map{ $0.0 }
//    }
    func allKeysForValue(val : Value) -> [Key] {
        return self.filter { $1 == val }.map { $0.0 }
    }
    func someKeyFor(value: Value) -> Key? {
        
        guard let index = indexOf({ $0.1 == value }) else {
            return nil
        }
        
        return self[index].0
        
    }
}