Robolayout

The default auto layout API is cumbersome to work with. At Robocat we made a few extensions to NSLayoutConstraint and UIView in order to make a tolerable auto layout API.

Installation

Either manually build the framework and import it into your project or install it using Carthage.

Add github "robocat/Robolayout" to your Cartfile and run carthage update. Drag the framework into your project.

Quick overview

Below is a quick overview of the API. Most of the methods should be self-explanatory. With the use of Swifts default parameters, the API become very concise but allow you to go into detail when needed.

Directly setting width and height

setWidthEqual(constant: CGFloat)
setHeightEqual(constant: CGFloat)
setWidthEqual(view: UIView, multiplier: CGFloat = 1)
setHeightEqual(view: UIView, multiplier: CGFloat = 1)

Spacing to edges

setLeadingToSuperview(relation relation: NSLayoutRelation = .Equal, constant: CGFloat = 0, priority: UILayoutPriority = 1000)
setTrailingToSuperview(relation relation: NSLayoutRelation = .Equal, constant: CGFloat = 0, priority: UILayoutPriority = 1000)
setTopToSuperview(relation relation: NSLayoutRelation = .Equal, constant: CGFloat = 0, priority: UILayoutPriority = 1000)
setBottomToSuperview(relation relation: NSLayoutRelation = .Equal, constant: CGFloat = 0, priority: UILayoutPriority = 1000)
constraints(vertical vertical: String? = nil, horizontal: String? = nil, _ views: [String : UIView])

The last method lets you configure the constraints using a visual format.

Centering

setCenterVerticallyInSuperview(constant constant: CGFloat = 0, priority: UILayoutPriority = 1000)
setCenterHorizontallyInSuperview(constant constant: CGFloat = 0, priority: UILayoutPriority = 1000)

Content hugging and compression resistance

The following variables on instances of UIView lets you configure the content hugging and compression resistance.

horizontalCompressionResistance
verticalCompressionResistance 
horizontalHuggingPriority
verticalHuggingPriority

Going into detail

A lot of the time you will use the above methods. The below method lays out to views relative to each other.

constraint(item: UIView, _ attribute: NSLayoutAttribute, _ relation: NSLayoutRelation, _ item2: UIView? = nil, _ attribute2: NSLayoutAttribute = .NotAnAttribute, multiplier: CGFloat = 1, constant: CGFloat = 0, priority: UILayoutPriority = 1000)

Sometimes you are interested in positioning views relative to the objects conforming to UILayoutSupport, e.g. topLayoutGuide and bottomLayoutGuide of UIViewController. In those cases you use the below method.

constraintToLayoutSupport(item: UIView, _ attribute: NSLayoutAttribute, _ relation: NSLayoutRelation, _ item2: UILayoutSupport, _ attribute2: NSLayoutAttribute = .NotAnAttribute, multiplier: CGFloat = 1, constant: CGFloat = 0, priority: UILayoutPriority = 1000)

Keeping references

All methods either return an instance or an array of NSLayoutConstraint, depending on whether a single or multiple constraints where added.

translatesAutoresizingMaskIntoConstraints

Robolayout will always set translatesAutoresizingMaskIntoConstraints of any views associated with the operation to false. This is by design. In most cases you are interested in having the property set to false. However, in some cases it must be true. This includes but is not limited to the content view of instances of UIViewTableViewCell and UICollectionView and the root view of a UIViewController. Remember to manually set translatesAutoresizingMaskIntoConstraints to true in those cases.