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iOS Introduction to Auto Layout in iOS Auto Layout in Code Constraints in Code

Mit Sengupta
Mit Sengupta
13,823 Points
Posted by Mit Sengupta
Mit Sengupta
13,823 Points

What am I doing wrong?

Here's what I wrote :

class MyViewController: UIViewController {

let sampleView = UIView()

override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(sampleView)
}

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    sampleView.translatesAutoresizingMaskIntoConstraints = false

    // Add constraints below

    let sampleViewHeightConstraints = NSLayoutConstraint(item: sampleView, attribute: .Height, relatedBy: .Equal,
    toItem: view, attribute: .NotAnAttribute, multiplier: 1.0, constant: 50.0)

    let sampleViewWidthConstraints = NSLayoutConstraint(item: sampleView, attribute: .Width, relatedBy: .Equal,
    toItem: view, attribute: .NotAnAttribute, multiplier: 1.0, constant: 50.0) 


    let sampleViewCenterXConstraints = NSLayoutConstraint(item: sampleView, attribute: .CenterX, relatedBy: .Equal, 
    toItem: view, attribute: .CenterX, multiplier: 1.0, constant: 0.0) 

    let sampleViewCenterYConstraints = NSLayoutConstraint(item: sampleView, attribute: .CenterY, relatedBy: .Equal,
    toItem: view, attribute: .CenterY, multiplier: 1.0, constant: 0.0)



    view.addConstraints([sampleViewHeightConstraints, sampleViewWidthConstraints, sampleViewCenterXConstraints, 
    sampleViewCenterYConstraints])

}

}

2 Answers

Jeroen de Vrind
Jeroen de Vrind
29,772 Points
Jeroen de Vrind
Jeroen de Vrind
29,772 Points

Depends on what you're trying to achieve. But I assume you want to make the sampleView as wide and as high as the view. You should set the attribute for the width and height constraint not to .NotAnAttribute but to the .Height and .Width attribute of the view. You can give the sampleView a backgroundColor to see it with sampleView.backgroundColor = UIColor.blueColor() for example in viewDidLoad() before you add it as a subView.

Ben Shockley
Ben Shockley
6,094 Points
Ben Shockley
Ben Shockley
6,094 Points

For the height and width attributes, you need to set the toItem: parameter to nil. That should get you going.