ios - 添加按钮以查看以编程方式创建

Question

我有一个以编程方式创建的 View ，如下所示

  let viewOne = UIView()
        viewOne.contentMode = .scaleAspectFit
        viewOne.backgroundColor = UIColor.blue
        viewOne.layer.masksToBounds = true
        viewOne.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(viewOne)

    NSLayoutConstraint.activate([
        viewOne.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        viewOne.centerYAnchor.constraint(equalTo: view.centerYAnchor),
        viewOne.heightAnchor.constraint(equalToConstant:200),
        viewOne.widthAnchor.constraint(equalToConstant:200)])

我有以下以编程方式创建的按钮，如下所示，

    let button = UIButton()
    button.frame = CGRect(x: 125, y: 125, width: 100, height: 50)
    button.backgroundColor = UIColor.green
    button.setTitle("Ok", for: .normal)
    button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
    viewOne.addSubview(button)

如何将按钮 添加到viewOne 的中心。提前致谢。

Answer 1

你可以试试

let viewOne = UIView()
viewOne.contentMode = .scaleAspectFit
viewOne.backgroundColor = UIColor.blue
viewOne.layer.masksToBounds = true
viewOne.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(viewOne)

let button = UIButton() 
button.backgroundColor = UIColor.green
button.setTitle("Ok", for: .normal)
button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside) 
button.translatesAutoresizingMaskIntoConstraints = false
viewOne.addSubview(button)

NSLayoutConstraint.activate([

    viewOne.centerXAnchor.constraint(equalTo: view.centerXAnchor),
    viewOne.centerYAnchor.constraint(equalTo: view.centerYAnchor),
    viewOne.heightAnchor.constraint(equalToConstant:200),
    viewOne.widthAnchor.constraint(equalToConstant:200),

    button.centerXAnchor.constraint(equalTo: viewOne.centerXAnchor),
    button.centerYAnchor.constraint(equalTo: viewOne.centerYAnchor),  
    button.heightAnchor.constraint(equalToConstant:100),
    button.widthAnchor.constraint(equalToConstant:50)

])

---

提示:

您可以选择删除这 2 个约束，因为默认情况下按钮具有固有内容大小，但如果您需要固定内容，请保留它们

 button.heightAnchor.constraint(equalToConstant:100),
 button.widthAnchor.constraint(equalToConstant:50)