API没有改变——只有语法改变了。你可以创建一个UIButton并像这样添加它:

var button = UIButton(frame: CGRectMake(0, 0, 50, 50))
self.view.addSubview(button) // assuming you're in a view controller

这是可能的。除了使用swift语法之外，您几乎可以以相同的方式完成所有操作。例如，你可以用这样的代码创建一个UIButton:

 var button: UIButton = UIButton(frame: CGRectMake(0, 0, 100, 100))

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")
}

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")
 }

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);

}

 var sampleButton:UIButton?

 override func viewDidLoad() {
  super.viewDidLoad()

 }
 override func viewDidAppear(animated: Bool) {

  sampleButton = UIButton(type: .RoundedRect)
  //sampleButton.frame = CGRect(x:50, y:500, width:70, height:50)

  sampleButton!.setTitle("Sample \n UI Button", forState: .Normal)
  sampleButton!.titleLabel?.lineBreakMode = .ByWordWrapping
  sampleButton!.titleLabel?.textAlignment = .Center
  sampleButton!.setTitleColor(UIColor.whiteColor(), forState: .Normal)
  sampleButton!.layer.cornerRadius = 6
  sampleButton!.backgroundColor = UIColor.redColor().colorWithAlphaComponent(0.6)
  sampleButton?.tintColor =  UIColor.brownColor()


  //Add padding around text
  sampleButton!.titleEdgeInsets = UIEdgeInsetsMake(-10,-10,-10,-10)
  sampleButton!.contentEdgeInsets = UIEdgeInsetsMake(5,5,5,5)

  //Action set up
  sampleButton!.addTarget(self, action: "sampleButtonClicked", forControlEvents: .TouchUpInside)
  self.view.addSubview(sampleButton!)


  //Button Constraints:
  sampleButton!.translatesAutoresizingMaskIntoConstraints = false

  //To anchor above the tab bar on the bottom of the screen:
  let bottomButtonConstraint = sampleButton!.bottomAnchor.constraintEqualToAnchor(bottomLayoutGuide.topAnchor, constant: -20)

  //edge of the screen in InterfaceBuilder:
  let margins = view.layoutMarginsGuide
  let leadingButtonConstraint = sampleButton!.leadingAnchor.constraintEqualToAnchor(margins.leadingAnchor)

  bottomButtonConstraint.active = true
  leadingButtonConstraint.active = true


 }
 func sampleButtonClicked(){

  print("sample Button Clicked")

 }