RubyMotion UIBarButtonItem Helper

layouts.rb

# Example:
#  self.navigationItem.leftBarButtonItems = [
#    ui_bar_button_item('1'){App.alert('One')},
#    ui_bar_button_item('2'){App.alert('Two')}
#  ]
def ui_bar_button_item(title, &block)
  item = UIBarButtonItem.alloc.initWithTitle(title, style: UIBarButtonItemStylePlain, target: block, action: :call)
  item.instance_variable_set('@_target', block) # retain
  item
end

Line #8 instance_variable_set is critical because the block doesn't seem to be retained in UIBarButtonItem.

I'm not sure if this will create memory leaks or not :/