LayoutConstraint

Expressive NSLayoutConstraints with Swift, inspired by Jonathan 'Wolf' Rentzsch's AutoLayoutShorthand: https://github.com/rentzsch/AutoLayoutShorthand

Usage

Given two views, v1 and v2:

let v1 = NSView(frame: NSRect.zeroRect)
let v2 = NSView(frame: NSRect.zeroRect)
v1.addSubview(v2)

Add constraints in shorthand form like so:

v1.addConstraints([
	v1.layoutCenterY == v2.layoutCenterY,
	v1.layoutLeading == v2.layoutLeading,
	v1.layoutTrailing == v2.layoutTrailing
])
v2.addConstraint(v2.layoutHeight == 12)

You can optionally specify constants, multipliers, and priority inline with your definition:

v1.addConstraints([
	v1.layoutTop == v2.layoutTop && .constant(10) && .priority(750),
	v1.layoutBottom == v2.layoutBottom,
	v1.layoutLeading == v2.layoutLeading,
	v1.layoutTrailing == v2.layoutTrailing
])

Layout Expression Grammar

relation-expression :=
	layout-attribute ( '==' | '<=' | '>=' ) value 
	| layout-attribute ( '==' | '<=' | '>=' ) layout-attribute

option-expression := 
	.priority(value) 
	| .constant(value) 
	| .multiplier(value)

layout-expression := 
	relation-expression 
	| layout-expression '&&' option-expression

License

MIT license - please feel free to use this as you like!