gistfile1.txt

extension Array where Element: Hashable {
    func uniqueElements() -> [Element] {
        return uniqueElements(by: { $0 })
    }

    func uniqueElements<T: Hashable>(by uniqueValue: (Element) -> T) -> [Element] {
        var uniqueElements: [Array.Element] = []
        var set: Set<T> = Set()
        for element in self {
            let value = uniqueValue(element)
            if set.contains(value) {
                continue
            }
            set.insert(value)
            uniqueElements.append(element)
        }
        return uniqueElements
    }
}