Make a UIButton programmatically in Swift

Question

I am trying to build UIs programmatically with Swift.

How can I get this action working?

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: "pressed", forControlEvents: .TouchUpInside)
    self.view.addSubview(myFirstLabel)
    self.view.addSubview(myFirstButton)
}

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

Solution 1

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 = .red
    myFirstLabel.textAlignment = .center
    myFirstLabel.numberOfLines = 5
    myFirstLabel.frame = CGRect(x: 15, y: 54, width: 300, height: 500)
    myFirstButton.setTitle("✸", for: .normal)
    myFirstButton.setTitleColor(.blue, for: .normal)
    myFirstButton.frame = CGRect(x: 15, y: -50, width: 300, height: 500)
    myFirstButton.addTarget(self, action: #selector(pressed), for: .touchUpInside)
}

@objc func pressed() {
    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.

Solution 2

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")
}

Solution 3

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
            }

Solution 4

Swift 4

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

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

}

Solution 5

You should be able to create a customize UI button programmatically by accessing the titleLabel property of UIButton.

Per Class Reference in Swift: Regarding the titleLabel property, it says that "although this property is read-only, its own properties are read/write. Use these properties primarily to configure the text of the button."

In Swift, you can directly modify the properties of titleLabel like such:

let myFirstButton = UIButton()
myFirstButton.titleLabel!.text = "I made a label on the screen #toogood4you"
myFirstButton.titleLabel!.font = UIFont(name: "MarkerFelt-Thin", size: 45)
myFirstButton.titleLabel!.textColor = UIColor.red
myFirstButton.titleLabel!.textAlignment = .center
myFirstButton.titleLabel!.numberOfLines = 5
myFirstButton.titleLabel!.frame = CGRect(x: 15, y: 54, width: 300, height: 500)

Edit

Swift 3.1 Syntax

View more solutions

Comments

[Benr783]

The app still crashes when I press the button.

[Dash]

Sorry fixed. The function shouldn't be nested.

[user2202911]

i tried running this code and it is not working for me. Non of the chidlren of titleLabel seem to exist

[juniorgarcia]

Hey, can you tell me the logic behind the colon we need to add after the string that represents the action?

[HughHughTeotl]

@chorajunior The colon is needed because the pressed function takes an argument.

[Dave G]

Inversely, anyone reading this may also want to know that if your button action references a function that takes no parameter, the colon is not needed and may even cause an error if not removed.

[Felipe]

Thanks, m8! Starting up with Swift today so everything is kind of strange (:

[arbel03]

Colon only in functions that take only 1 parameter.

[evanflash]

It's worth noting that the pressed function needs to be public, at least that has been my experience.

[evanflash]

whoops, too late to edit my comment, but here's some more clarification about access control using addTarget stackoverflow.com/questions/25056278/…

[corykon]

After following everything described above I kept getting the unrecognized selector crash. Found the answerI needed here: stackoverflow.com/a/29409052/2311702

[nyxee]

how does getCurrentLocation help us to get the location please?

[7stud]

@nyxee, The question here was about how to programmatically make a button. Getting the location of a user has nothing to do with making a button. To get a user's location see here; developer.apple.com/reference/corelocation/cllocationmanager‌​. If you can’t figure it out, ask your own question please.

[ArgaPK]

@n.by.n how to pass argument on this method buttonClicked()?

[Pradumna Patil]

Without @objc for selector function it is not accepting.

[Milo Chen]

'''@objc func buttonAction() { //some Action }'''. <-- Should add @objc

[ShadeToD]

Remember that you can't use addTarget with action inside a closure.