RxSwift：Driver与UI控件初体验

输入电话号码的区号和八位数主体号码，下面的Label实时更新最新的输入，如果区号为3位数，点击按钮，按钮名字变成“变！”

Ps：目前还不会，同时满足上面两位，下面三位的的约束，以后会更新的

文件名：ViewController.swift

//
//  ViewController.swift
//  RxSwiftTest
//
//  Created by travey on 2018/11/5.
//  Copyright © 2018年 ZhouShijie. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa
import SnapKit

    class ViewController: UIViewController {
        
        var textField1: UITextField!
        var textField2: UITextField!
        var label: UILabel!
        var btn: UIButton!
        let disposeBag = DisposeBag()

        override func viewDidLoad() {
            
            textField1 = UITextField()
            textField2 = UITextField()
            label = UILabel()
            btn = UIButton()
            
            textField1.layer.borderWidth = 1
            textField2.layer.borderWidth = 1
            label.textAlignment = .center
            btn.setTitle("点我", for: .normal)
            btn.layer.borderWidth = 1
            btn.setTitleColor(UIColor.black, for: .normal)
            
            view.addSubview(textField1)
            view.addSubview(textField2)
            view.addSubview(label)
            view.addSubview(btn)
            
            textField1.snp.makeConstraints { (make) in
                make.centerX.equalToSuperview()
                make.top.equalToSuperview().offset(200)
                make.height.equalTo(30)
                make.width.equalTo(200)
            }
            
            textField2.snp.makeConstraints { (make) in
                make.centerX.equalToSuperview()
                make.top.equalTo(textField1.snp.bottom).offset(30)
                make.height.equalTo(30)
                make.width.equalTo(200)
            }
            
            label.snp.makeConstraints { (make) in
                make.centerX.equalToSuperview()
                make.top.equalTo(textField2.snp.bottom).offset(30)
                make.height.equalTo(30)
                make.width.equalTo(500)
            }
            
            btn.snp.makeConstraints { (make) in
                make.centerX.equalToSuperview()
                make.top.equalTo(label.snp.bottom).offset(30)
                make.height.equalTo(30)
                make.width.equalTo(40)
            }
            
            Observable.combineLatest(textField1.rx.text.orEmpty, textField2.rx.text.orEmpty){
                "你输入的电话号码是\($0)-\($1)"
            }
            .asDriver(onErrorJustReturn: "")
            .drive(label.rx.text)
            .disposed(by: disposeBag)
            
            textField1.rx.text.orEmpty.asObservable().asDriver(onErrorJustReturn: "")
            .map{ $0.count == 3 }
            .drive(btn.rx.isEnabled)
            .disposed(by: disposeBag)
            
            btn.rx.tap
            .subscribe(onNext: { [weak self] in
                    self?.btn.setTitle("变！", for: .normal)
                })
            .disposed(by: disposeBag)
        }
    }