UIAlertView, UIActionSheet

app_delegate.rb

class MyViewController < UIViewController
  def viewDidLoad
    super
    view.backgroundColor = UIColor.whiteColor

    button = UIButton.buttonWithType(UIButtonTypeRoundedRect).tap do |b|
      b.frame = [[30.0, 30.0], [200.0, 30.0]]
      b.setTitle("Click", forState:UIControlStateNormal)
      b.addTarget(self, action: 'open_action_sheet:', forControlEvents: UIControlEventTouchUpInside)
    end
    view.addSubview(button)

    alert_button = UIButton.buttonWithType(UIButtonTypeRoundedRect).tap do |b|
      b.frame = [[30.0, 80.0], [200.0, 30.0]]
      b.setTitle("Click", forState:UIControlStateNormal)
      b.addTarget(self, action: 'open_alert:', forControlEvents: UIControlEventTouchUpInside)
    end
    view.addSubview(alert_button)
  end

  def open_alert(sender)
    alert = UIAlertView.alloc.initWithTitle('ALERT', message:'hogehoge', delegate:self, cancelButtonTitle:'Cancel', otherButtonTitles:nil)
    alert.show
  end

  def open_action_sheet(sender)
    as = UIActionSheet.alloc.initWithTitle("SELECT", delegate: self, cancelButtonTitle: "CANCEL", destructiveButtonTitle: "OK", otherButtonTitles: nil)
    as.showInView(view)
  end

  def actionSheet(actionSheet, clickedButtonAtIndex: buttonIndex)
    puts "press #{buttonIndex}"
  end
end

class AppDelegate
  def application(application, didFinishLaunchingWithOptions:launchOptions)
    @window = UIWindow.alloc.initWithFrame(UIScreen.mainScreen.bounds)
    my_controller = MyViewController.new
    @window.rootViewController = my_controller
 
    @window.makeKeyAndVisible
    true
  end
end