Single to Taple in RxSwift

synchronize.swift

func synchronize<T>(_ single: Single<T>) -> (element: T?, error: Error?) {
    var element: T?
    var error: Error?
    let condition = NSCondition()
    condition.lock()
    _ = single.subscribe({ event in
        condition.lock()
        switch event {
        case .success(let elm): element = elm
        case .error(let err): error = err
        }
        condition.signal()
        condition.unlock()
    })
    condition.wait()
    condition.unlock()
    return (element: element, error: error)
}