Adding button to view created programatically

Question

I have a view that is created programatically as follows

  let viewOne = UIView()
        viewOne.contentMode = .scaleAspectFit
        viewOne.backgroundColor = UIColor.blue
        viewOne.layer.masksToBounds = true
        viewOne.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(viewOne)

    NSLayoutConstraint.activate([
        viewOne.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        viewOne.centerYAnchor.constraint(equalTo: view.centerYAnchor),
        viewOne.heightAnchor.constraint(equalToConstant:200),
        viewOne.widthAnchor.constraint(equalToConstant:200)])

I have the following button that is created programmatically as follows,

    let button = UIButton()
    button.frame = CGRect(x: 125, y: 125, width: 100, height: 50)
    button.backgroundColor = UIColor.green
    button.setTitle("Ok", for: .normal)
    button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
    viewOne.addSubview(button)

How do I add the button to the center of viewOne. Thanks in advance.

It would be the same as the code you posted to put viewOne in the center. Just change the views referenced in the constraints. — rmaddy
– rmaddy, Commented Jun 20, 2019 at 16:12

Shehata Gamal · Accepted Answer · 2019-06-20 16:23:21Z

You can try

let viewOne = UIView()
viewOne.contentMode = .scaleAspectFit
viewOne.backgroundColor = UIColor.blue
viewOne.layer.masksToBounds = true
viewOne.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(viewOne)

let button = UIButton() 
button.backgroundColor = UIColor.green
button.setTitle("Ok", for: .normal)
button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside) 
button.translatesAutoresizingMaskIntoConstraints = false
viewOne.addSubview(button)

NSLayoutConstraint.activate([

    viewOne.centerXAnchor.constraint(equalTo: view.centerXAnchor),
    viewOne.centerYAnchor.constraint(equalTo: view.centerYAnchor),
    viewOne.heightAnchor.constraint(equalToConstant:200),
    viewOne.widthAnchor.constraint(equalToConstant:200),

    button.centerXAnchor.constraint(equalTo: viewOne.centerXAnchor),
    button.centerYAnchor.constraint(equalTo: viewOne.centerYAnchor),  
    button.heightAnchor.constraint(equalToConstant:100),
    button.widthAnchor.constraint(equalToConstant:50)

])

Tip:

you can optionally remove these 2 constraints as the button has intrinsic content size by default but if you need a fixed content leave them

 button.heightAnchor.constraint(equalToConstant:100),
 button.widthAnchor.constraint(equalToConstant:50)

Lê Công · Accepted Answer · 2019-06-20 16:21:07Z

0

Button it self has the width and height. So you do not have to fix it

button.centerXAnchor.constraint(equalTo: viewOne.centerXAnchor)
button.centerYAnchor.constraint(equalTo: viewOne.centerYAnchor)

answered Jun 20, 2019 at 16:21

Lê Công

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Comments

rs7 · Accepted Answer · 2019-06-20 16:25:42Z

You can either use autolayout, as shown below:

    let button = UIButton()
    button.translatesAutoresizingMaskIntoConstraints = false
    button.backgroundColor = UIColor.green
    button.setTitle("Ok", for: .normal)
    button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
    viewOne.addSubview(button)
    NSLayoutConstraint.activate([
    button.centerXAnchor.constraint(equalTo: viewOne.centerXAnchor),
    button.centerYAnchor.constraint(equalTo: viewOne.centerYAnchor),
    button.heightAnchor.constraint(equalToConstant:50),
    button.widthAnchor.constraint(equalToConstant:100)])

Or place your button manually, after doing some calculation.

let button = UIButton(frame: CGRect(x: 50, y: 75, width: 100, height: 50))
viewOne.addSubview(button)

I obtained x and y as follows: x = viewOne width/2 - button width/2 = 200/2 - 100/2 = 50 y = viewOne height/2 - button height/2 = 200/2 - 50/2 = 75

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