UIButton转UIBarButtonItem

let leftButton = UIButton(type: .Custom);

let leftItem = UIBarButtonItem(customView: leftButton)

navigationItem.leftBarButtonItem = leftItem;

UIButton *leftButton = [UIButton buttonWithType:UIButtonTypeCustom];

UIBarButtonItem *leftItem = [[UIBarButtonItem alloc]initWithCustomView:leftButton];

self.navigationItem.leftBarButtonItem = leftItem;