override func viewDidLoad() {

super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    var imageView = UIImageView(frame: CGRectMake(100, 150, 150, 150));
    var image = UIImage(named: "BattleMapSplashScreen.png");
    imageView.image = image;
    self.view.addSubview(imageView);

}

步骤1:创建一个新项目

步骤2:在ViewController.swift中

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // CODE
        let btn = UIButton(type: UIButtonType.System) as UIButton        
        btn.backgroundColor = UIColor.blueColor()
        btn.setTitle("CALL TPT AGENT", forState: UIControlState.Normal)
        btn.frame = CGRectMake(100, 100, 200, 100)
        btn.addTarget(self, action: "clickMe:", forControlEvents: UIControlEvents.TouchUpInside)
        self.view.addSubview(btn)

    }

    func clickMe(sender:UIButton!) {
      print("CALL")
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

在Swift 4.2中编写下面的示例代码，用于以编程方式添加按钮。

override func viewDidLoad() {
    super.viewDidLoad()
        let myButton = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 50))
        myButton.backgroundColor = .green
        myButton.setTitle("Hello UIButton", for: .normal)
        myButton.addTarget(self, action: #selector(myButtonAction), for: .touchUpInside)
        self.view.addSubview(myButton)
}

 @objc func myButtonAction(sender: UIButton!) {
    print("My Button tapped")
}

你可以这样创建，也可以这样添加动作....

import UIKit

let myButton = UIButton(frame: CGRect(x: 0, y: 0, width: 50, height: 50))

init(nibName nibNameOrNil: String!, bundle nibBundleOrNil: NSBundle!)
{       super.init(nibName: nibName, bundle: nibBundle) 
        myButton.targetForAction("tappedButton:", withSender: self)
}

func tappedButton(sender: UIButton!)
{ 
     println("tapped button")
}

下面是一个完整的解决方案，以编程方式添加一个UIButton与targetAction。 斯威夫特2.2

override 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来正确地为每个iPhone屏幕放置按钮可能更好。

Swift 3.1的更新代码:

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")
}

Swift 4.2的更新代码:

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声明为private或internal，上述方法仍然有效。

    // UILabel:
    let label = UILabel()
    label.frame = CGRectMake(35, 100, 250, 30)
    label.textColor = UIColor.blackColor()
    label.textAlignment = NSTextAlignment.Center
    label.text = "Hello World"
    self.view.addSubview(label)

    // UIButton:
    let btn: UIButton = UIButton(type: UIButtonType.Custom) as UIButton
    btn.frame = CGRectMake(130, 70, 60, 20)
    btn.setTitle("Click", forState: UIControlState.Normal)
    btn.setTitleColor(UIColor.blackColor(), forState: .Normal)
    btn.addTarget(self, action:Selector("clickAction"), forControlEvents: UIControlEvents.TouchUpInside)
    view.addSubview(btn)


    // Button Action:
    @IBAction func clickAction(sender:AnyObject)
    {
        print("Click Action")
    }