swift - BarButtonItem not appearing -

i have simple + button on right side add rows tableview, button not appearing. how implement it

    let addbutton = uibutton()     addbutton.settitle("+", forstate: .normal)     let addview = uibarbuttonitem(customview: addbutton)     self.navigationitem.rightbarbuttonitem = addview             addbutton.addtarget(self, action: #selector(self.addrow), forcontrolevents: uicontrolevents.touchupinside) 

note, use same exact implementation hamburger button appear. working hamburger button implementation

    let navicon = uibutton(type: uibuttontype.system)     navicon.setimage(defaultmenuimage(), forstate: uicontrolstate.normal)     navicon.frame = cgrectmake(0, 0, 30, 30)     let menu = uibarbuttonitem(customview: navicon)     self.navigationitem.leftbarbuttonitem = menu     self.view.addgesturerecognizer(self.revealviewcontroller().pangesturerecognizer())     navicon.addtarget(self.revealviewcontroller(), action: #selector(swrevealviewcontroller.revealtoggle(_:)), forcontrolevents: .touchupinside) 

why happening?

try:

let addbutton = uibutton(type: .custom) addbutton.frame = cgrectmake(0, 0, 44, 44)