Small useful operators from RxSwiftExt, my top-3.

RxSwiftExt_smallFriends.swift

//______ unwrap
Observable.from([1, 2, nil, 4])
    .unwrap()
    .bind { print($0) }
// Output: 1, 2, 4

//______  filterMap
Observable.of(1, 2, 3, 4, 5, 6)
    .filterMap { $0 % 2 == 0 ? .map($0 * 2) : .ignore }
// Output: 4, 8, 12

//______  apply
func requestPolicy(_ request: Single<Response>) -> Single<Response> {
    return request.retry(maxAttempts)
        .do(onNext: sideEffect)
        .map { Response.success }
        .catchError { error in Observable.just(parseRequestError(error: error)) }
}
  
let resilientRequest = request.apply(requestPolicy)