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 Using Layout Anchors

Posted by David Bales
David Bales
3,822 Points

I require assistance.

In the editor, you've been provided with a view controller subclass that contains two instances of UIView as stored properties. The work to set up blueView has already been done; you need to set up greenView.

To set up the green view add the following constraints: Pin to the bottom of blueView with 8 point spacing Pin to left and right margins with 8 point spacing Add height constraint of 75 points.

For this exercise you may use the verbose NSLayoutConstraint APIs or layout anchors to create constraints.

I have 0 ideas on what to do here.

layout.swift 
class MyViewController: UIViewController {

    let blueView = UIView()
    let greenView = UIView()

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(greenView)
        view.addSubview(blueView)
    }

    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        blueView.translatesAutoresizingMaskIntoConstraints = false
        greenView.translatesAutoresizingMaskIntoConstraints = false

        NSLayoutConstraint.activateConstraints([
            NSLayoutConstraint(item: blueView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 100.0),
            NSLayoutConstraint(item: blueView, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 150.0),
            NSLayoutConstraint(item: blueView, attribute: .Left, relatedBy: .Equal, toItem: view, attribute: .LeftMargin, multiplier: 1.0, constant: 8.0),
            NSLayoutConstraint(item: blueView, attribute: .Top, relatedBy: .Equal, toItem: self.topLayoutGuide, attribute: .Bottom, multiplier: 1.0, constant: 8.0),
            NSLayoutConstraint(item: blueView, attribute: .Right, relatedBy: .Equal, toItem: view, attribute: .RightMargin, multiplier: 1.0, constant: -8.0)
        ])

        // Add constraint code below
    }
}

2 Answers

U Belfast
U Belfast
6,439 Points
U Belfast
U Belfast
6,439 Points

Hi,

Well, you can find the hint which add height constraint of 75 points to the greenView below: It is left to add another 3 constraints

class MyViewController: UIViewController {

let blueView = UIView()
let greenView = UIView()

override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(greenView)
    view.addSubview(blueView)
}

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    blueView.translatesAutoresizingMaskIntoConstraints = false
    greenView.translatesAutoresizingMaskIntoConstraints = false

    NSLayoutConstraint.activateConstraints([
        NSLayoutConstraint(item: blueView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 100.0),
        NSLayoutConstraint(item: blueView, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 150.0),
        NSLayoutConstraint(item: blueView, attribute: .Left, relatedBy: .Equal, toItem: view, attribute: .LeftMargin, multiplier: 1.0, constant: 8.0),
        NSLayoutConstraint(item: blueView, attribute: .Top, relatedBy: .Equal, toItem: self.topLayoutGuide, attribute: .Bottom, multiplier: 1.0, constant: 8.0),
        NSLayoutConstraint(item: blueView, attribute: .Right, relatedBy: .Equal, toItem: view, attribute: .RightMargin, multiplier: 1.0, constant: -8.0)
    ])

    // Add constraint code below

    NSLayoutConstraint.activateConstraints([
        NSLayoutConstraint(item: greenView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 75.0),
    ])
}

}

Ryan Sady
Ryan Sady
20,594 Points
Ryan Sady
Ryan Sady
20,594 Points

Hi David,

I'm not sure if you've figured out the issue or not, but you need to use upper camel case for the attributes. .Height, .Width, .NotAnAttribue (which was illustrated above by U Belfast).