Abandoned dictionary diffing in swift

dictionary_diff.swift

import Foundation

extension Dictionary {
    static func keyDifference<Value: Equatable>(dictionary1 dic1: Dictionary<Key, Value>, dictionary2 dic2: Dictionary<Key, Value>, inout inserted:  Set<Key>, inout deleted: Set<Key>, inout updated:Set<Key>, inout unchanged: Set<Key>) {
        let keys1 = Set(dic1.keys.array)
        let keys2 = Set(dic2.keys.array)
        let allKeys = keys1.union(keys2)
        
        inserted = []
        deleted = []
        updated = []
        unchanged = []
        for key in allKeys {
            switch (dic1[key], dic2[key]) {
            case (.None, .Some(let _)):
                inserted.insert(key)
            case (.Some(let _), .None):
                deleted.insert(key)
            case (.Some(let v1), .Some(let v2)):
                if v1 == v2 {
                    unchanged.insert(key)
                } else {
                    updated.insert(key)
                }
            default:
                assertionFailure("Key \"\(key)\" must exist in either one or another dictionary")
                break
            }
        }
    }
}

extension NSDictionary {
    static func wml_keyDifferenceBetweenDictionary(dic1: NSDictionary, andDictionary dic2: NSDictionary, inserted: UnsafeMutablePointer<NSSet>, deleted: UnsafeMutablePointer<NSSet>, updated: UnsafeMutablePointer<NSSet>, unchanged: UnsafeMutablePointer<NSSet>) {
        if let dic1 = dic1 as? [String: NSObject],
            dic2 = dic2 as? [String: NSObject] {
                var outInserted: Set<String> = [], outDeleted: Set<String> = [], outUpdated: Set<String> = [], outUnchanged: Set<String> = []
                [String: NSObject].keyDifference(dictionary1: dic1, dictionary2: dic2, inserted: &outInserted, deleted: &outDeleted, updated: &outUpdated, unchanged: &outUnchanged)
                inserted.initialize(outInserted)
                deleted.initialize(outDeleted)
                updated.initialize(outUpdated)
                unchanged.initialize(outUnchanged)
        } else {
            assertionFailure("Can't process dictionaries: unexpected types")
        }
    }
}