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iOS Introduction to Auto Layout in iOS Auto Layout in Code Using Layout Anchors

Matthew Ingram
PLUS
Matthew Ingram
Courses Plus Student 4,718 Points
Posted by Matthew Ingram
Matthew Ingram
Courses Plus Student 4,718 Points

Not really sure why this anchoring is not compiling correctly

It works for the trailing anchor but not the leadingAnchor and when i put it into xcode i didn't see a problem

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.activate([
            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.activate([
        greenView.bottomAnchor.constraint(equalTo: blueView.bottomAnchor, constant: 8),
        greenView.leadingAnchor.constraint(equalTo: view.layoutMarginsGuide.leadingAnchor, constant: 8),
        greenView.trailingAnchor.constraint(equalTo: view.layoutMarginsGuide.trailingAnchor, constant: 8),
        greenView.heightAnchor.constraint(equalToConstant: 75.0)
        ])

    }
}