以编程方式使用addSubview时，Swift 3 UIView不会呈现UILabel

Question

我有几种用例，需要以编程方式向StackViews和其他控件添加标签和“容器”视图（例如UIView）。

我无法渲染标签，并且我确定它是我忽略设置的简单布局标志。

下面的示例：使用UIView.addSubview（）以编程方式呈现UILabel

import UIKit

class TestViewController: UIViewController {

  var label = UILabel()
  var container = UIView()

  open override func viewDidLoad() {
    super.viewDidLoad()

    container = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))

    label.text = "Hello World!"
    label.textColor = .white


    container.addSubview(label)  // <- This does not work

    self.view.addSubview(container)

  }


}

以下代码块有效，但没有利用自动版式。任何援助将不胜感激。

import UIKit

class TestViewController: UIViewController {

  var label = UILabel()
  var container = UIView()

  open override func viewDidLoad() {
    super.viewDidLoad()

    container = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))

    label.text = "Hello World!"
    label.textColor = .white


    container.layout(label).topLeft() // <- This works

    self.view.addSubview(container)

  }


}

Answer 1

弄清楚了...

import UIKit

class TestViewController: UIViewController {

  var label = UILabel()
  var container = UIView()

  open override func viewDidLoad() {
    super.viewDidLoad()

    container = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))

    label.text = "Hello World!"
    label.textColor = .white
    label.frame = container.frame


    container.addSubview(label)

    self.view.addSubview(container)

  }


}