RxSwift - Validation sample

ValidationViewController.swift

import UIKit
import RxSwift
import RxCocoa

let requiredUserNameLength = 5
let requiredPasswordLength = 5

let limitUserNameLength = 20

class ValidationViewController: UIViewController {

    @IBOutlet weak var userNameText: UITextField!
    @IBOutlet weak var userNameRemainLabel: UILabel!
    @IBOutlet weak var userNameValidationLabel: UILabel!

    @IBOutlet weak var passwordText: UITextField!
    @IBOutlet weak var passwordInvalidLabel: UILabel!
    
    @IBOutlet weak var loginButton: UIButton!
    
    let disposeBag = DisposeBag()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let userNameValid: Observable<Bool> = userNameText.rx_text
            .map{ text -> Bool in
                text.characters.count >= requiredUserNameLength
            }
            .shareReplay(1)
        
        let userNameRemainText: Observable<String> = userNameText.rx_text
            .map { text -> String in
                let currentLength = text.characters.count
                return "\(currentLength)/\(limitUserNameLength)"
            }
        
        let passwordValid: Observable<Bool> = passwordText.rx_text
            .map { text -> Bool in
                text.characters.count >= requiredPasswordLength
            }
            .shareReplay(1)
        
        let everythingValid: Observable<Bool>
            = Observable.combineLatest(userNameValid, passwordValid) { $0 && $1 }
        
        userNameValid
            .bindTo(userNameValidationLabel.rx_hidden)
            .addDisposableTo(disposeBag)
        
        userNameRemainText
            .bindTo(userNameRemainLabel.rx_text)
            .addDisposableTo(disposeBag)
        
        passwordValid
            .bindTo(passwordInvalidLabel.rx_hidden)
            .addDisposableTo(disposeBag)
        
        everythingValid
            .bindTo(loginButton.rx_enabled)
            .addDisposableTo(disposeBag)
    }
}