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

Posted by Selvaraj Thangaselvam
Selvaraj Thangaselvam
1,922 Points

Introduction to Auto Layout in iOS

How to create pin to left and right margins with 8 point spacing

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)
        ])

         NSLayoutConstraint.activateConstraints([ greenView.topAnchor.constraintEqualToAnchor(blueView.bottomAnchor, constant: 8.0),

            greenView.leftAnchor.constraintEqualToAnchor(view.layoutMarginsGuide.leftAnchor, constant: -8.0),

            greenView.rightAnchor.constraintEqualToAnchor(view.layoutMarginsGuide.rightAnchor, constant: 8.0),

            greenView.heightAnchor.constraintEqualToConstant(75)
        ])


        // Add constraint code below
    }
}