RxSwift版实现实时检测textFiled输入值呈现不同状态

rx_text

import UIKit
import RxCocoa
import RxSwift

class Demo6: UIViewController {
    
    @IBOutlet weak var usernameTextfield: UITextField!
    @IBOutlet weak var passwordTextfield: UITextField!
    @IBOutlet weak var registerButton: UIButton!
   
    let disposeBag = DisposeBag()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let nameObserable = usernameTextfield.rx_text.shareReplay(1).map {
            $0.characters.count > 6
        }
        let pwdObserable = passwordTextfield.rx_text.shareReplay(1).map {
            $0.characters.count >= 8
        }
        
        _ = nameObserable.bindTo(usernameTextfield.ex_validState).addDisposableTo(disposeBag)
        _ = pwdObserable.bindTo(passwordTextfield.ex_validState).addDisposableTo(disposeBag)
        
        _ = Observable.combineLatest(nameObserable, pwdObserable) {$0 && $1}.bindTo(registerButton.ex_validState).addDisposableTo(disposeBag)
        
        _ = registerButton.rx_tap.shareReplay(1).subscribeNext { [weak self] in
            
            self?.buttonTapped()
        }
    }

    func buttonTapped()  {
         print("Button tapped")
    }
}
/// 扩展
extension UITextField {
    var ex_validState:AnyObserver<Bool>{
        return UIBindingObserver(UIElement: self) { textfield, valid in
            textfield.backgroundColor = valid ? UIColor.clearColor() : UIColor.grayColor()
           textfield..textColor= valid ? UIColor.grayColor() : UIColor.whiteColor()
            }.asObserver()
    }
}
extension UIButton {
    var ex_validState:AnyObserver<Bool>{
        return UIBindingObserver(UIElement: self) { button, valid in
            button.enabled = valid
            button.backgroundColor = valid ? UIColor.redColor() : UIColor.darkGrayColor()
            }.asObserver()
    }
}

常规做法

因为textField代理事件不能做到实时检测，所以...
相比RxSwift太逊色...如果还要继续进行其他交互，不可想象代码的增加量及维护性

import UIKit
class Demo6: UIViewController {
    
    @IBOutlet weak var usernameTextfield: UITextField! {
        didSet {
            usernameTextfield.backgroundColor = UIColor.grayColor()
            usernameTextfield.textColor = UIColor.whiteColor()
            usernameTextfield.addTarget(self, action: #selector(Demo6.textFieldDidChange(_:)), forControlEvents: .EditingChanged)
        }
    }
    @IBOutlet weak var passwordTextfield: UITextField! {
        didSet {
            passwordTextfield.backgroundColor = UIColor.grayColor()
            passwordTextfield.textColor = UIColor.whiteColor()
            passwordTextfield.addTarget(self, action: #selector(Demo6.textFieldDidChange(_:)), forControlEvents: .EditingChanged)
        }
    }
    
    @IBOutlet weak var registerButton: UIButton! {
        didSet {
            registerButton.userInteractionEnabled = false
            registerButton.backgroundColor = UIColor.grayColor()
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

    }
    
    func textFieldDidChange(sender:UITextField) {
        
        let usernameCount = usernameTextfield.text?.characters.count
        let passwordCount = passwordTextfield.text?.characters.count
        
        usernameTextfield.backgroundColor = usernameCount > 6 ? UIColor.clearColor() : UIColor.grayColor()
        usernameTextfield.textColor = usernameCount > 6 ? UIColor.grayColor() : UIColor.whiteColor()

        passwordTextfield.backgroundColor = passwordCount >= 8 ? UIColor.clearColor() : UIColor.grayColor()
        passwordTextfield.textColor = passwordCount >= 8 ? UIColor.grayColor() : UIColor.whiteColor()
        
        if usernameCount > 6 && passwordCount >= 8 {
            registerButton.userInteractionEnabled = true
            registerButton.backgroundColor = UIColor.redColor()
        } else {
            registerButton.userInteractionEnabled = false
            registerButton.backgroundColor = UIColor.grayColor()
        }
    }
    
    @IBAction func buttonTapped(sender: AnyObject) {
         print("Button tapped")
    }
}