如何只显示一次登录屏幕？

Question

I'm showing the login screen when the user first opens the app. After the user successfully logs in, I store a session id in NSUserDefaults . Then next time when the user opens the app, I check whether the session id is set. If it is set then I don't want to show the login screen.

So on first time I want to show main_controller but when user opens the app second time after successfully logging in then I want to show test_controller.rb .

Question

Where should I control this flow?

I'm not sure how to check the session id the second time when the app opens up.

Here is my app_delegate.rb

class AppDelegate
  attr_reader :window

  def application(application, didFinishLaunchingWithOptions:launchOptions)
    @window = UIWindow.alloc.initWithFrame(UIScreen.mainScreen.bounds)

    main_controller = MainController.alloc.initWithNibName(nil, bundle: nil)
    @window.rootViewController = UINavigationController.alloc.initWithRootViewController(main_controller)

    @window.makeKeyAndVisible
    true
  end
end

main_controller.rb

class MainController < UIViewController
  def viewDidLoad
    super

    self.edgesForExtendedLayout = UIRectEdgeNone

    rmq.stylesheet = MainStylesheet
    init_nav
    rmq(self.view).apply_style :root_view

    @username = rmq.append(UITextField, :username).focus.get
    @password = rmq.append(UITextField, :password).focus.get
    @sessionId = NSUserDefaults.standardUserDefaults
    puts @sessionId["sessionId"]
    if @sessionId["sessionId"] == nil
      rmq.append(UIButton, :submit_button).on(:touch) do |sender|
        puts "pressed #{@username.text} #{@password.text}"
        login_user (@username.text, @password.text)
      end
    end
  end

  def login_user(uname, pwd)
      client = AFMotion::Client.build("http://localhost:9000/") do
        header "Accept", "application/json"
        header "Content-Type", "application/json"
        request_serializer :json
        response_serializer :json
      end

      client.post("user/signup", username: uname, password: pwd) do |result|
        @sessionId["sessionId"] = result.object["sessionId"]
      end
  end

  def init_nav
    self.title = "Main"
  end
end

and finally the test_controller.rb

class TestController < UIViewController

  def viewDidLoad
    super

    # Sets a top of 0 to be below the navigation control
    self.edgesForExtendedLayout = UIRectEdgeNone

    rmq.stylesheet = MainStylesheet
    init_nav
    rmq(self.view).apply_style :root_view

  end

  def init_nav
    self.title = "TEST"
  end
end

Answer 1

I think you can use some sort of helper class like this

AuthManager.rb

class AuthManager
  attr_accessor :sessionId

  def self.instance
    Dispatch.once { @instance ||= new}
    @instance
  end

  def init
    @keychain = KeychainItemWrapper.alloc.initWithIdentifier('EthanApp', accessGroup: nil)
    self.sessionId = @keychain.objectForKey KSecAttrAccount
  end

  def need_login?
    return (self.sessionId.nil? || self.sessionId.empty?)
  end

  def login(username, password)
    client = AFMotion::Client.build('http://localhost:9000/') do
      header 'Accept', 'application/json'
      header 'Content-Type', 'application/json'
      request_serializer :json
      response_serializer :json
    end
    client.post('user/signup', username: uname, password: pwd) do |result|
      ap result
      ap result.object
      if result.success?
        @keychain.setObject result.object[:sessionId], forKey: KSecAttrAccount
      else
        App.alert('login failed: invalid username and/or password')
      end
    end
  end

  def logout
    @keychain.setObject nil, forKey: KSecAttrAccount
  end
end

Add this to your app_delegate.rb

AuthManager.instance.init # initialize singleton object

main_controller.rb

# You can control your login screen by call this method
if AuthManager.instance.need_login?
  rmq.append(UIButton, :submit_button).on(:touch) do |sender|
      AuthManager.instance.login(username, password)
  end
else
  # Display TestController
end

Answer 2

I would suggest that you reconsider your program flow. The case where the user is already logged in should be considered as the most common one, with the need to log in as an exception.

You can then make your test_controller the "main controller". In the viewDidAppear method you can check your session details from NSUSerDefsults and display the login screen modally when required.

Answer 3

看一下在Xcode5中加载不同的viewcontroller ...这个问题是相似的，但是出于ObjC的目的...也许您从中得到了这个主意。

Answer 4

Your AppDelegate is the appropriate place to put this. It contains various "app" events, and also controls startup flow.

Like Paulw11 mentioned, your test_controller should be your main_controller, then create a "login_controller".

class AppDelegate
  attr_reader :window

  def application(application, didFinishLaunchingWithOptions:launchOptions)
    @window = UIWindow.alloc.initWithFrame(UIScreen.mainScreen.bounds)

    if logged_in?
      create_main_controller
    else
      create_login_controller
    end

    @window.makeKeyAndVisible
    true
  end

  def logged_in?
    # Your logic here
  end

  def create_main_controller
    main_controller = MainController.new
    @window.rootViewController = UINavigationController.alloc.initWithRootViewController(main_controller)
  end

  def create_login_controller
    @window.rootViewController = LoginController.new
  end
end

When the app starts up, you check if the user is already logged in, if they are, set the rootViewController to be you main_controller, if not, set it to be the login_controller.

Once the user logs in set their info in NSUserDefaults then change the rootViewController:

rmq.app.delegate.create_main_controller