orderedDictionary

import UIKit

struct OrderedDictionary<Tk: Hashable, Tv> {
    
    var keys: Array<Tk>
    var values: Dictionary<Tk,Tv>
    
    
    // 1
    mutating func insert(value: Tv, forKey key: Tk, atIndex index: Int) -> Tv?
    {
        var adjustedIndex = index
        
        // 2
        let existingValue = self.values[key]
        if existingValue != nil {
            // 3
            let existingIndex = find(self.keys, key)!
            
            // 4
            if existingIndex < index {
                adjustedIndex--
            }
            self.keys.removeAtIndex(existingIndex)
        }
        
        // 5
        self.keys.insert(key, atIndex:adjustedIndex)
        self.values[key] = value
        
        // 6
        return existingValue
    }

}