Make a UIButton programmatically in Swift

Question

I am trying to build UI\'s programmatically. How do I get this action working? I am developing with Swift.

Code in viewDidLoad:

over         


        

Answer 1

Yeah in simulator. Some times it wont recognise the selector there is a bug it seems. Even i faced not for your code , then i just changed the action name (selector). It works

let buttonPuzzle:UIButton = UIButton(frame: CGRectMake(100, 400, 100, 50))
buttonPuzzle.backgroundColor = UIColor.greenColor()
buttonPuzzle.setTitle("Puzzle", forState: UIControlState.Normal)
buttonPuzzle.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
buttonPuzzle.tag = 22;
self.view.addSubview(buttonPuzzle)

An example selector function is here:

func buttonAction(sender:UIButton!) {
    var btnsendtag:UIButton = sender
    if btnsendtag.tag == 22 {            
        //println("Button tapped tag 22")
    }
}

Answer 2

Swift 4

    private func createButton {
        let sayButtonT = UIButton(type: .custom)
        sayButtonT.addTarget(self, action: #selector(sayAction(_:)), for: .touchUpInside)
    }

    @objc private func sayAction(_ sender: UIButton?) {

    }

Answer 3

You're just missing the colon at the end of the selector name. Since pressed takes a parameter the colon must be there. Also your pressed function shouldn't be nested inside viewDidLoad.

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    let myFirstLabel = UILabel()
    let myFirstButton = UIButton()
    myFirstLabel.text = "I made a label on the screen #toogood4you"
    myFirstLabel.font = UIFont(name: "MarkerFelt-Thin", size: 45)
    myFirstLabel.textColor = UIColor.redColor()
    myFirstLabel.textAlignment = .Center
    myFirstLabel.numberOfLines = 5
    myFirstLabel.frame = CGRectMake(15, 54, 300, 500)
    myFirstButton.setTitle("✸", forState: .Normal)
    myFirstButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
    myFirstButton.frame = CGRectMake(15, -50, 300, 500)
    myFirstButton.addTarget(self, action: #selector(myClass.pressed(_:)), forControlEvents: .TouchUpInside)
    self.view.addSubview(myFirstLabel)
    self.view.addSubview(myFirstButton)
}

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

EDIT: Updated to reflect best practices in Swift 2.2. #selector() should be used rather than a literal string which is deprecated.

Answer 4

UIButton with constraints in iOS 9.1/Xcode 7.1.1/Swift 2.1:

import UIKit
import MapKit

class MapViewController: UIViewController {  

    override func loadView() {
        mapView = MKMapView()  //Create a view...
        view = mapView         //assign it to the ViewController's (inherited) view property.
                               //Equivalent to self.view = mapView

        myButton = UIButton(type: .RoundedRect)  //RoundedRect is an alias for System (tested by printing out their rawValue's)
        //myButton.frame = CGRect(x:50, y:500, width:70, height:50)  //Doesn't seem to be necessary when using constraints.
        myButton.setTitle("Current\nLocation", forState: .Normal)
        myButton.titleLabel?.lineBreakMode = .ByWordWrapping  //If newline in title, split title onto multiple lines
        myButton.titleLabel?.textAlignment = .Center
        myButton.setTitleColor(UIColor.whiteColor(), forState: .Normal)
        myButton.layer.cornerRadius = 6   //For some reason, a button with type RoundedRect has square corners
        myButton.backgroundColor = UIColor.redColor().colorWithAlphaComponent(0.5) //Make the color partially transparent
        //Attempt to add padding around text. Shrunk the frame when I tried it.  Negative values had no effect.
        //myButton.titleEdgeInsets = UIEdgeInsetsMake(-10,-10,-10,-10)
        myButton.contentEdgeInsets = UIEdgeInsetsMake(5,5,5,5)  //Add padding around text.

        myButton.addTarget(self, action: "getCurrentLocation:", forControlEvents: .TouchUpInside)
        mapView.addSubview(myButton)

        //Button Constraints:
        myButton.translatesAutoresizingMaskIntoConstraints = false //***
        //bottomLayoutGuide(for tab bar) and topLayoutGuide(for status bar) are properties of the ViewController
        //To anchor above the tab bar on the bottom of the screen:
        let bottomButtonConstraint = myButton.bottomAnchor.constraintEqualToAnchor(bottomLayoutGuide.topAnchor, constant: -20) //Implied call of self.bottomLayoutGuide. Anchor 20 points **above** the top of the tab bar.
        //To anchor to the blue guide line that is inset from the left 
        //edge of the screen in InterfaceBuilder:
        let margins = view.layoutMarginsGuide  //Now the guide is a property of the View.
        let leadingButtonConstraint = myButton.leadingAnchor.constraintEqualToAnchor(margins.leadingAnchor)

        bottomButtonConstraint.active = true
        leadingButtonConstraint.active = true
    }


    func getCurrentLocation(sender: UIButton) {
        print("Current Location button clicked!")
    }

The button is anchored to the bottom left corner, above the tab bar.

Answer 5

Swift 2.2 Xcode 7.3

Since Objective-C String Literals are deprecated now for button callback methods

let button:UIButton = UIButton(frame: CGRectMake(100, 400, 100, 50))
button.backgroundColor = UIColor.blackColor()
button.setTitle("Button", forState: UIControlState.Normal)
button.addTarget(self, action:#selector(self.buttonClicked), forControlEvents: .TouchUpInside)
self.view.addSubview(button)

func buttonClicked() {
     print("Button Clicked")
}

Swift 3 Xcode 8

let button:UIButton = UIButton(frame: CGRect(x: 100, y: 400, width: 100, height: 50))
button.backgroundColor = .black
button.setTitle("Button", for: .normal)
button.addTarget(self, action:#selector(self.buttonClicked), for: .touchUpInside)
self.view.addSubview(button)

func buttonClicked() {
    print("Button Clicked")
}

Swift 4 Xcode 9

let button:UIButton = UIButton(frame: CGRect(x: 100, y: 400, width: 100, height: 50))
button.backgroundColor = .black
button.setTitle("Button", for: .normal)
button.addTarget(self, action:#selector(self.buttonClicked), for: .touchUpInside)
self.view.addSubview(button)

@objc func buttonClicked() {
    print("Button Clicked")
}

Answer 6

Swift 4/5

let button = UIButton(frame: CGRect(x: 20, y: 20, width: 200, height: 60))
 button.setTitle("Email", for: .normal)
 button.backgroundColor = .white
 button.setTitleColor(UIColor.black, for: .normal)
 button.addTarget(self, action: #selector(self.buttonTapped), for: .touchUpInside)
 myView.addSubview(button)



@objc func buttonTapped(sender : UIButton) {
                //Write button action here
            }