Gemfile

source "https://rubygems.org"

gem "rake"

# Screens
gem "ProMotion"

gem 'motion-layout'

home_screen.rb

class HomeScreen < PM::Screen
  title "Home"

  def on_load
    # After view is first loaded
    set_nav_bar_button :right, title: "Help", action: :show_help
    @state = UILabel.new
    @state.font = UIFont.systemFontOfSize(30)
    @state.text = 'Tap to start'
    @state.textAlignment = UITextAlignmentCenter
    @state.textColor = UIColor.whiteColor
    @state.backgroundColor = UIColor.clearColor

    @action = UIButton.buttonWithType(UIButtonTypeRoundedRect)
    @action.setTitle('Start', forState:UIControlStateNormal)
    @action.setTitle('Stop', forState:UIControlStateSelected)
    @action.addTarget(self, action:'actionTapped', forControlEvents:UIControlEventTouchUpInside)

    Motion::Layout.new do |layout|
      layout.view view
      layout.subviews "state" => @state, "action" => @action
      layout.metrics "top" => 200, "margin" => 20, "height" => 40
      layout.vertical "|-top-[state(==height)]-margin-[action(==height)]"
      layout.horizontal "|-margin-[state]-margin-|"
      layout.horizontal "|-margin-[action]-margin-|"
    end
  end

  def actionTapped
    if @timer
      @timer.invalidate
      @timer = nil
    else
      @duration = 0
      @timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target:self, selector:'timerFired', userInfo:nil, repeats:true)
    end
    @action.selected = [email protected]?
  end

  def timerFired
    @state.text = "%.1f" % (@duration += 0.1)
  end

  def show_help
    open HelpScreen
  end

end