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klsaerf
klsaerf

Reputation: 23

How to make constraints to change depending on device's height (xcode)

I would like to make a button close to the bottom of the screen. If for ex. user's device is iPhone 5S, 10 points but for iPhone 11, 20 point etc. I couldn't find how to make it like

constraint = height / constant

so higher the device higher the button will be. How can I achieve this programmatically or from Xcode UI?

Upvotes: 0

Views: 65

Answers (2)

Mat
Mat

Reputation: 6324

Maybe you can get the height of your devices' windows and multiply it for the ratio?

var button : UIButton = {
    let b = UIButton()
    b.translatesAutoresizingMaskIntoConstraints = false
    b.backgroundColor = .red
    return b
}()

override func viewDidLoad() {
    super.viewDidLoad()

    let screenSize = UIScreen.main.bounds
    let height = screenSize.height
    let ratio:CGFloat = 0.05 // you can change this
    let bottomConstraint = height*ratio
    print(bottomConstraint) // this would print 44.80 on the iPhone 11 and 33.35 on the iPhone 8

    self.view.addSubview(button)
    button.heightAnchor.constraint(equalToConstant: 50).isActive = true
    button.widthAnchor.constraint(equalToConstant: 200).isActive = true
    button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
    // then you applied the variable constraint
    button.bottomAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor, constant: -bottomConstraint).isActive = true
}

IPHONE8

IPHONE11

Upvotes: 1

Jay Lee
Jay Lee

Reputation: 1902

In your viewDidLoad, get the reference for the view to setup as so:

class ViewController: UIViewController {
  var targetView: UIView! // or @IBOutlet if you created it from the Interface Builder (IB)
  private let ratio: CGFloat = 0.05

  override func viewDidLoad() {
    super.viewDidLoad()
    // The following line enables you to programmatically set constraint using AutoLayout
    targetView.translatesAutoresizingMaskIntoConstraints = false

    // Get the height of the screen
    let height = UIScreen.main.bounds.height

    targetView.bottomAnchor.constraint(
        equalTo: view.safeAreaLayoutGuide.bottomAnchor,
        constant: -height * ratio
    ).isActive = true
    // Set the other necessary constraints
  }

Upvotes: 0

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