"在调用中缺少参数'style'的参数"创建系统UIBarButtonItem时出错

Question

我不明白为什么编译器要求在这个系统风格的UIBarButtonItem初始化程序中使用style参数的参数 - 它首先没有该参数.救命？这是Swift的错误吗？

class ExpensesViewController: UIViewController {

    lazy var newExpenseBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Add, target: self, action: Selector("newExpenseBarButtonItemTapped:"))

    func newExpenseBarButtonItemTapped() {

    }

}

Answer 1

这将删除编译器错误消息：

class ExpensesViewController: UIViewController {

    lazy var newExpenseBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.UIBarButtonSystemItemAdd.value, 
                 target:self, action:Selector("newExpenseBarButtonItemTapped:"))

    func newExpenseBarButtonItemTapped() {

    }

}

.Add不是有效值