小编Zha*_*tov的帖子

我试图以编程方式创建一个按钮并使用SnapKit应用约束.一切正常,但当我应用约束,因为make.center.equalTo(self.view) 它崩溃给我这条消息"终止应用程序由于未捕获的异常无法安装约束,原因:视图之间没有共同的超级视图".这是我创建按钮的代码:

    func createButton() {
    let button   = UIButton(type: UIButtonType.System) as UIButton
    button.backgroundColor = UIColor.greenColor()
    button.setTitle("Test Button", forState: UIControlState.Normal)
    button.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)

    button.snp_makeConstraints { (make) -> Void in
        make.width.equalTo(200)
        make.height.equalTo(70)
        make.center.equalTo(self.view)
    }

    self.view.addSubview(button)
}