Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Martel Storm
Martel Storm
4,157 Points
Posted by Martel Storm
Martel Storm
4,157 Points

Constraints in Code: Code Challenge: It says I can't use an array. I say bologna! Where did I mess up?

I might be retarded

layout.swift 
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
        func sampleViewConstraints() {
            sampleView.translatesAutoresizingMaskIntoConstraints = false

            let sampleViewCenterX = NSLayoutConstraint(item: sampleView, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 0.0)

            let sampleViewCenterY = NSLayoutConstraint(item: sampleView, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1.0, constant: 0.0)

            let sampleViewHeight = NSLayoutConstraint(item: sampleView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)

            let sampleViewWidth = NSLayoutConstraint(item: sampleView, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)

            view.addConstraint([
                sampleViewWidth,
                sampleViewHeight,
                sampleViewCenterX,
                sampleViewCenterY])
        }
    }
}

1 Answer

Aniruddha Shukla
Aniruddha Shukla
2,846 Points
Aniruddha Shukla
Aniruddha Shukla
2,846 Points

The method name is addConstraints and not addConstraint. It takes in an array of Constraints. Also, another thing that I see off is whats another method doing in the viewWillLayoutSubviews?

Try this with the fixed changes

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
            sampleView.translatesAutoresizingMaskIntoConstraints = false

            let sampleViewCenterX = NSLayoutConstraint(item: sampleView, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 0.0)

            let sampleViewCenterY = NSLayoutConstraint(item: sampleView, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1.0, constant: 0.0)

            let sampleViewHeight = NSLayoutConstraint(item: sampleView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)

            let sampleViewWidth = NSLayoutConstraint(item: sampleView, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 50.0)

            view.addConstraints([
                sampleViewWidth,
                sampleViewHeight,
                sampleViewCenterX,
                sampleViewCenterY])

    }
}