AMGAutolayout

How it works

Those are some examples of what is possible to do with AMGAutolayout:

//With operators

//Directly from layout property (this doesn't make `translatesAutoresizingMaskIntoConstraints = false`)
secondTitleLabel.layout.top == textLabel.layout.bottom + 50

//Or with makeLayout which makes `translatesAutoresizingMaskIntoConstraints = false` to the current view
secondTitleLabel.makeLayout {
    $0.left == titleLabel.layout.left
    $0.right == titleLabel.layout.right - 30
    $0.height == 50
}

secondTextLabel.makeLayout {
    topConstraint2 = $0.top == secondTitleLabel.layout.bottom + 20
    $0.centerX <= secondTitleLabel.layout.centerX
    $0.width == secondTitleLabel.layout.width - 50
    $0.height == secondTitleLabel.layout.height * 3 + 50
}

frameView.makeLayout {
    $0.top >= secondTextLabel.layout.bottom + 20
    $0.left == backgroundView.layout.left + 20
    $0.right <= backgroundView.layout.right - 20
    $0.aspectRatio(5)
    $0.bottom == backgroundView.layout.bottom - 20
}

frameView2.makeLayout {
    $0.centerSuperview()
    $0.width <= 50
    $0.height >= 20
}

frameView3.makeLayout {
    $0.center(frameView2)
    $0.width == 50
    $0.height == 20
}

backgroundView.makeLayout {
    $0.fillSuperview(with: UIEdgeInsets(top: 20, left: 20, bottom: 20, right: 20), relativeToSafeArea: true)
}

//Without operators

titleLabel.makeLayout {
    topConstraint = $0.top.equal(to: backgroundView.layout.top, offsetBy: 20)
    $0.left.equal(to: backgroundView.layout.left, offsetBy: 20)
    $0.right.equal(to: backgroundView.layout.right, offsetBy: -20)
    $0.height.equal(to: 52)
}

textLabel.makeLayout {
    $0.top.equal(to: titleLabel.layout.bottom, offsetBy: 20)
    $0.centerX.equal(to: titleLabel.layout.centerX)
    $0.width.equal(to: titleLabel.layout.width, constant: 10)
    $0.height.equal(to: titleLabel.layout.height, multiplier: 2, constant: 10)
}

The view.layout variable have all this properties:

public lazy var leading = property(with: view.leadingAnchor)
public lazy var trailing = property(with: view.trailingAnchor)
public lazy var left = property(with: view.leftAnchor)
public lazy var right = property(with: view.rightAnchor)
public lazy var top = property(with: view.topAnchor)
public lazy var bottom = property(with: view.bottomAnchor)
public lazy var width = dimensionProperty(with: view.widthAnchor)
public lazy var height = dimensionProperty(with: view.heightAnchor)
public lazy var centerX = property(with: view.centerXAnchor)
public lazy var centerY = property(with: view.centerYAnchor)

//Safe area
public lazy var safeTop = property(with: view.safeAnchorContainer.topAnchor)
public lazy var safeBottom = property(with: view.safeAnchorContainer.bottomAnchor)
public lazy var safeLeft = property(with: view.safeAnchorContainer.leftAnchor)
public lazy var safeRight = property(with: view.safeAnchorContainer.rightAnchor)
public lazy var safeLeading = property(with: view.safeAnchorContainer.leadingAnchor)
public lazy var safeTrailing = property(with: view.safeAnchorContainer.trailingAnchor)
public lazy var safeWidth = dimensionProperty(with: view.safeAnchorContainer.widthAnchor)
public lazy var safeHeight = dimensionProperty(with: view.safeAnchorContainer.heightAnchor)
public lazy var safeCenterX = property(with: view.safeAnchorContainer.centerXAnchor)
public lazy var safeCenterY = property(with: view.safeAnchorContainer.centerYAnchor)

All this properties are available:

var leadingAnchor: NSLayoutXAxisAnchor { get }
var trailingAnchor: NSLayoutXAxisAnchor { get }
var leftAnchor: NSLayoutXAxisAnchor { get }
var rightAnchor: NSLayoutXAxisAnchor { get }
var topAnchor: NSLayoutYAxisAnchor { get }
var bottomAnchor: NSLayoutYAxisAnchor { get }
var widthAnchor: NSLayoutDimension { get }
var heightAnchor: NSLayoutDimension { get }
var centerXAnchor: NSLayoutXAxisAnchor { get }
var centerYAnchor: NSLayoutYAxisAnchor { get }

The operators that can be used are:

• property1 == property2

• property1 >= property2

• property1 <= property2

• dimensionProperty1 == dimensionProperty2

• dimensionProperty1 >= dimensionProperty2

• dimensionProperty1 <= dimensionProperty2

• dimensionProperty1 == constant

• dimensionProperty1 >= constant

• dimensionProperty1 <= constant

And for the part of property2 you can also do:

• property2 + constant
• property2 - constant

And for the part of dimensionProperty2:

• dimensionProperty2 * multiplier
• dimensionProperty2 * multiplier + constant
• dimensionProperty2 * multiplier - constant

Requirements

iOS 9.0 is required

Installation

AMGAutolayout is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'AMGAutolayout'

Author

AlbertMontserrat, albert.montserrat.gambus@gmail.com

This library follows and extends the custom DSL created by John Sundell in this post:

https://www.swiftbysundell.com/posts/building-dsls-in-swift

In this library there's lot of additions like:

• Working directly with dimension constants like $0.height == 30
• Working directly with properties and get completely rid of view.xyzAnchor
• Adding lofs of extension, as, for example, having the safe area with a simple $0.top = $1.layout.safeTop
• Allowing multiplier with custom operators and even combine multiplier with offset to do something like $0.height = $1.layout.height * 2 + 10
• Return the generated constraint even with the operators function to be able to handle next changes in the view controller. Also added as a @discardableResult to avoid warnings in regular usage
• And much more...

License

AMGAutolayout is available under the MIT license. See the LICENSE file for more info.