Although RubyMotion is great, sometimes is hard to know how to use some Cocoa methods or parameters. This is how you translate an action parameter (SEL)action:
UIBarButtonItem *refreshButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh
target:self
action:@selector(refreshMeasures)];
refreshButton = UIBarButtonItem.alloc.initWithBarButtonSystemItem(
UIBarButtonSystemItemRefresh, target:self, action:'refreshMeasures')
where refreshMeasures is a method defined in the class
def refreshMeasures
end