swift - BarButtonItem 没有出现

Question

我在右侧有一个简单的 + 按钮，用于将行添加到我的 tableView，但是该按钮没有出现。我是这样实现的

    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)

请注意，我对确实出现的汉堡包按钮使用了完全相同的实现。这是有效的汉堡包按钮实现

    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)

为什么会这样？

Answer 1

尝试:

let AddButton = UIButton(type: .Custom)
AddButton.frame = CGRectMake(0, 0, 44, 44)