ObservableType+IgnoreNil.swift

import RxSwift

extension Observable where Element: OptionalType {
    
    func ignoreNil() -> Observable<Element.T> {
        filter { $0.optional != nil }.map { $0.optional! }
    }
}


extension Observable {
    
    func compactMap<R: OptionalType>(_ transform: @escaping (Observable.E) throws -> R) -> Observable<R.T> {
        map(transform).ignoreNil()
    }
}


protocol OptionalType {
    associatedtype T
    
    var optional: T? { get }
}


extension Optional: OptionalType {
    
    var optional: Wrapped? { self }
}