Making compiler happy

As far as I understand `itemWithLabel:` support to return `RIButtonItem` or one of the subclasses
If not casted to RIButton, I'm getting `Sending 'void (^__strong)(void)' to parameter of incompatible type 'SEL' (aka 'SEL *')` compiler error
Although I do understand it might be a compiler issue (it thinks newItem is a `UIBarButtonItem` instance), 
it prevents me from compiling project:)
Thank you!