如何以编程方式创建按钮？

Question

如何UIButton在Swift中以编程方式创建图形元素（如a ）？我试图在视图中创建并添加按钮，但无法进行。

Answer 1

以下是UIButton使用targetAction以编程方式添加的完整解决方案。Swift 2.2override func viewDidLoad() {  super.viewDidLoad()  let button = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 50))  button.backgroundColor = .greenColor()  button.setTitle("Test Button", forState: .Normal)  button.addTarget(self, action: #selector(buttonAction), forControlEvents: .TouchUpInside)  self.view.addSubview(button)}func buttonAction(sender: UIButton!) {  print("Button tapped")}使用NSLayoutConstraint而不是frame为每个iPhone屏幕正确放置按钮可能更好。更新了Swift 3.1的代码：override func viewDidLoad() {  super.viewDidLoad()  let button = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 50))  button.backgroundColor = .green  button.setTitle("Test Button", for: .normal)  button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)  self.view.addSubview(button)}func buttonAction(sender: UIButton!) {  print("Button tapped")}更新了Swift 4.2的代码：override func viewDidLoad() {  super.viewDidLoad()  let button = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 50))  button.backgroundColor = .green  button.setTitle("Test Button", for: .normal)  button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)  self.view.addSubview(button)}@objc func buttonAction(sender: UIButton!) {  print("Button tapped")}如果func buttonAction声明private或上述仍然有效internal。