文本没有出现在swift中的UIButton上

Question

对此我的头撞了一下.应该这么简单.

在里面的操场上跑步 MyClass:

func configureButton(){
    let btn: UIButton = UIButton(frame: CGRectMake(5, 75, 90, 20))
    btn.backgroundColor = UIColor.greenColor()
    btn.addTarget(self,
                  action: #selector(MyClass.buttonTapped),
                  forControlEvents: UIControlEvents.TouchUpInside)
    addSubview(btn)
    btn.setTitleColor(UIColor.blackColor(), forState: .Normal)
    btn.titleLabel?.font = UIFont(name: "Helvetica", size: 40)
    btn.titleLabel?.text = "tap me"
  }

该按钮显示绿色,按下时可以工作,但不显示文本.

Answer 1

这条线错了:

btn.titleLabel?.text = "tap me"

不要试图像这样直接操纵按钮的标题标签文本.总是通过按钮的官方标题设置器,setTitle:forState:.