In rxswift I can't send one parameter to CombineLatest. What should I use for one parameter?

Question

In rxswift I can't send one parameter to CombineLatest. What should I use for one parameter?

import Foundation
import RxSwift

struct RegisterPhoneViewModel {

    var phoneNumberText = Variable<String>("")

    var isValid: Observable<Bool> {
        return Observable.combineLatest(phoneNumberText.asObservable()) {phoneNum in
            phoneNum.count >= 11
        }
    }
}

Answer 1

I had to use the ‍map like this

import Foundation
import RxSwift

struct RegisterPhoneViewModel {

    var phoneNumberText = Variable<String>("")


    var isValid: Observable<Bool> {
        return self.phoneNumberText.asObservable().map {phoneNum  in
            phoneNum.count >= 11
        }
    }

}