Swift 3

let button = UIButton()
button.frame = CGRect(x: self.view.frame.size.width - 60, y: 60, width: 50, height: 50)
button.backgroundColor = UIColor.red
button.setTitle("your Button Name", for: .normal)
button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
self.view.addSubview(button)

func buttonAction(sender: UIButton!) {
    print("Button tapped")
}

Swift 4+

 let button = UIButton()
 button.frame = CGRect(x: self.view.frame.size.width - 60, y: 60, width: 50, height: 50)
 button.backgroundColor = UIColor.red
 button.setTitle("Name your Button ", for: .normal)
 button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
 self.view.addSubview(button)

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

如何使用Swift 3.0来做到这一点。

func createButton() {
    let button = UIButton(type: .system)
    button.frame = CGRect(x: 100.0, y: 100.0, width: 100.0, height: 100.0)
    button.setTitle(NSLocalizedString("Button", comment: "Button"), for: .normal)
    button.backgroundColor = .green
    button.addTarget(self, action: #selector(buttonAction(sender:)), for: .touchUpInside)
    view.addSubview(button)
}

@objc func buttonAction(sender: UIButton) {
    print("Button pushed")
}

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。

            let myFirstButton = UIButton()
            myFirstButton.setTitle("Software Button", forState: .Normal)
            myFirstButton.setTitleColor(UIColor.redColor(), forState: .Normal)
            myFirstButton.frame = CGRectMake(100, 300, 150, 50)
            myFirstButton.backgroundColor = UIColor.purpleColor()
            myFirstButton.layer.cornerRadius = 14
            myFirstButton.addTarget(self, action: "pressed:", forControlEvents: .TouchUpInside)
            self.view.addSubview(myFirstButton)
            myFirstButton.hidden=true
            nameText.delegate = self


func pressed(sender: UIButton!) {
        var alertView = UIAlertView()
        alertView.addButtonWithTitle("Ok")
        alertView.title = "title"
        alertView.message = "message"
        alertView.show();
    }

 func viewDidLoad(){
                    saveActionButton = UIButton(frame: CGRect(x: self.view.frame.size.width - 60, y: 0, width: 50, height: 50))
                    self.saveActionButton.backgroundColor = UIColor(red: 76/255, green: 217/255, blue: 100/255, alpha: 0.7)
                    saveActionButton.addTarget(self, action: #selector(doneAction), for: .touchUpInside)
                    self.saveActionButton.setTitle("Done", for: .normal)
                    self.saveActionButton.layer.cornerRadius = self.saveActionButton.frame.size.width / 2
                    self.saveActionButton.layer.borderColor = UIColor.darkGray.cgColor
                    self.saveActionButton.layer.borderWidth = 1
                    self.saveActionButton.center.y = self.view.frame.size.height - 80
                    self.view.addSubview(saveActionButton)
        }

          func doneAction(){
          print("Write your own logic")
         }

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")
}