make Array unique

Array+Uniq.swift

extension Array {
    func uniqBy<KeyType: Hashable>(@noescape hash: (Element) -> KeyType) -> [Element] {
        var seen: [KeyType: Bool] = [:]
        return self.filter { element in
            let key = hash(element)
            if seen[key] == nil {
                seen[key] = true
                return true
            }
            return false
        }
    }

    mutating func uniqInPlaceBy<KeyType: Hashable>(@noescape hash: (Element) -> KeyType) {
        self = self.uniqBy(hash)
    }
}

extension Array where Element: Hashable {
    func uniq() -> [Element] {
        return self.uniqBy { $0 }
    }

    mutating func uniqInPlace() {
        self = self.uniq()
    }
}