ViewConstraints

Helper functions for UIView NSLayoutConstraints.

Installation

Swift Package Manager

Just add https://github.com/SlavaBreath/ViewConstraints.git to your package list

Usage

let view = UIView()
let containerView = UIView()

containerView.add(view)
    .fill(inside: containerView, offset: 12)

This will create four constraints, one for leading, trailing, top and bottom anchors with 12, 12, -12 and -12 constants respectively. Note that you don't have to call translatesAutoresizingMaskIntoConstraints = false since it's done automatically. Options for equalTo, greaterThanOrEqualTo and lessThanOrEqualTo are available. iOS 11 constraints for system spacing with multipliers are available as well.

let view = UIView()
let containerView = UIView()

containerView.add(view)
    .leading(equalTo: containerView, constant: 5)
    .trailing(equalTo: containerView, constant: -12)
    .top(equalTo: containerView)
    .bottom(equalTo: containerView, constant: -4)

This will create four constraints, one for leading, trailing, top and bottom anchors with 5, -12, 0 and -4 constants respectively. Please not that if you want to create constraints between same anchors of two views (leading and leading, for example) you can omit them in call. The same goes for UILayoutGuide.

let leadingView = UIView()
let trailingView = UIView()
let containerView = UIView()

containerView.add(leadingView)
    .leading(equalTo: containerView, constant: 5)
    .top(equalTo: containerView)
    .bottom(equalTo: containerView)
    
containerView.add(trailingView)
    .leading(equalTo: leadingView.trailingAnchor, constant: 12)
    .trailing(equalTo: containerView, constant: 5)
    .top(equalTo: containerView)
    .bottom(equalTo: containerView)

This will create a layout with two views, leading and trailing, which are inside a container and have a spacing of 12 between themselves and a horizontal padding of 5 to the container.

There is also a way to store the most recently created constraint from the chain

let view = UIView()
let containerView = UIView()

let heightConstraint = containerView.add(view)
    .fill(inside: containerView)
    .height(equalTo: 50)
    .constraint

This will return a constraint for heightAnchor with a constant of 50. In order to store constraints that are in the middle of a chain just break a chain to separate calls.

let view = UIView()
let containerView = UIView()

let leadingConstraint = containerView.add(view)
    .leading(equalTo: containerView)
    .constraint
    
let heightConstraint = containerView
    .trailing(equalTo: containerView)
    .top(equalTo: containerView)
    .bottom(equalTo: containerView)
    .height(equalTo: 50)
    .constraint

Please note that you cannot store a constraint by calling fill, size and center funcs since they create more than one constraints at the same time.