将此代码添加到viewDidLoad中 / /添加按钮

            var button=UIButton(frame: CGRectMake(150, 240, 75, 30))
            button.setTitle("Next", forState: UIControlState.Normal)
            button.addTarget(self, action: "buttonTapAction:", forControlEvents: UIControlEvents.TouchUpInside)
            button.backgroundColor = UIColor.greenColor()
            self.view.addSubview(button)

将这个函数写在它的外面，当你点击按钮时，这个函数将被调用

func buttonTapAction(sender:UIButton!)
{
    println("Button is working")
}

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))

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")
}

    // 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")
    }

Uilabel code 

var label: UILabel = UILabel()
label.frame = CGRectMake(50, 50, 200, 21)
label.backgroundColor = UIColor.blackColor()
label.textColor = UIColor.whiteColor()
label.textAlignment = NSTextAlignment.Center
label.text = "test label"
self.view.addSubview(label)

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")
}