NiceLayout

NiceLayout provides a concise fluent interface for setting up Auto Layout constraints in code. It builds on the system layout constraint APIs and can easily be integrated into an existing project.

// Before
myView.addSubview(button)
button.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
    button.leadingAnchor.constraint(equalTo: myView.leadingAnchor, constant: 16),
    button.trailingAnchor.constraint(equalTo: myView.trailingAnchor, constant: -16),
    button.topAnchor.constraint(equalTo: label.bottomAnchor),
    button.heightAnchor.constraint(equalToConstant: 44)
])

// After
myView.addSubview(button)
button.pin(.hEdges).to(.super).inset(16)
button.pin(.top).to(label, .bottom)
button.pin(.height).to(44)

Installation

CocoaPods

To integrate NiceLayout into your Xcode project using CocoaPods, specify it in your Podfile:

pod 'NiceLayout', '~> 0.0.1`

Manually

To integrate NiceLayout into your Xcode project manually, copy the contents of the Source folder into your project.

Usage

Adding constraints

The expression for adding a constraint takes the basic form of view.pin(...).to(...).

view1.pin(.leading).to(view2, .trailing)

view1.pin(.width).to(120)

When the same anchor is used for both views, it can be omitted in the to(...) call.

view1.pin(.leading).to(view2, .leading)
view1.pin(.leading).to(view2)

To set the constant for a constraint, append an offset(...) call.

view1.pin(.leading).to(view2).offset(16)

The inset(...) method works the same as offset(...), but flips the sign of the constant for trailing and bottom edges so that edges are always offset inwards.

view1.pin(.trailing).to(view2).offset(-16)
view1.pin(.trailing).to(view2).inset(16)

Composite anchors are also available for setting multiple constraints at once.

view1.pin(.center).to(view2)

view1.pin(.edges).to(view2).inset(16)

view1.pin(.size).to(width: 60, height: 80)

NiceLayout automatically sets translatesAutoresizingMaskIntoConstraints to false for the view on the left-hand side of the expression.

Superview constraints

When constraining a view to its superview, the shorthand value .super can be used as the target.

labelContainerView.addSubview(label)
label.pin(.leading).to(.super)
label.pin(.centerY).to(.super)

A view can also be constrained to its superview's safe area or layout margins.

view.addSubview(textView)
textView.pin(.top).to(.safeArea)
textView.pin(.hEdges).to(.margins)

Constraint options

The multiplier, priority, and relation of constraints can be set with additional method calls.

view1.pin(.width).to(view2).multiplier(0.5)

view1.pin(.height).to(600).priority(250)

view1.pin(.bottom).to(view2).inset(24).relation(.lessOrEqual)

Accessing raw NSLayoutConstraints

To access the underlying NSLayoutConstraints created by NiceLayout, use the constraint or constraints property on a constraint expression. These constraints may then be updated or deactivated as usual.

let widthConstraint: NSLayoutConstraint = view1.pin(.width).to(120).constraint

let edgeConstraints: [NSLayoutConstraint] = view1.pin(.edges).to(view2).constraints