Driftwood : A lightweight Swift library for AutoLayout

Requirements

iOS 8.0+/macOS 10.11+/tvOS 9.0+
Swift 4.2+

Usage

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

pod 'Driftwood'

Quick Start

Driftwood is easy to use, you can make full constraints satisfication in just a few code.

Let's say we want to layout a box that is constrained to it’s superview’s edges with 20pts of padding.

let box = UIView()
superview.addSubview(box)
box.dw.make().left(20).top(20).right(-20).bottom(-20)

Or another way:

let box = UIView()
superview.addSubview(box)
box.dw.make().edge(insets: UIEdgeInsets(top: 20, left: 20, bottom: 20, right: 20))

Attribute

All NSLayoutConstraint.Attribute cases are available in Driftwood.

Let's say view1 is at the bottom of view2, offset with 10pts.

view1.dw.make().top(10, to: view2.dw.bottom)

Full list of NSLayoutConstraint.Attribute:

`X-axis Attribute property`	`X-axis Attribute function`	`NSLayoutConstraint.Attribute`
`dw.left`	`dw.make().left()`	`.left`
`dw.right`	`dw.make().right()`	`.right`
`dw.leading`	`dw.make().leading()`	`.leading`
`dw.trailing`	`dw.make().trailing()`	`.trailing`
`dw.centerX`	`dw.make().centerX()`	`.centerX`
`dw.leftMargin`	`dw.make().leftMargin()`	`.leftMargin`
`dw.rightMargin`	`dw.make().rightMargin()`	`.rightMargin`
`dw.leadingMargin`	`dw.make().leadingMargin()`	`.leadingMargin`
`dw.trailingMargin`	`dw.make().trailingMargin()`	`.trailingMargin`

`Y-axis Attribute property`	`Y-axis Attribute function`	`NSLayoutConstraint.Attribute`
`dw.top`	`dw.make().top()`	`.top`
`dw.bottom`	`dw.make().bottom()`	`.bottom`
`dw.centerY`	`dw.make().centerY()`	`.centerY`
`dw.lastBaseline`	`dw.make().lastBaseline()`	`.lastBaseline`
`dw.firstBaseline`	`dw.make().firstBaseline()`	`.firstBaseline`
`dw.topMargin`	`dw.make().topMargin()`	`.topMargin`
`dw.bottomMargin`	`dw.make().bottomMargin()`	`.bottomMargin`
`dw.centerYWithinMargins`	`dw.make().centerYWithinMargins()`	`.centerYWithinMargins`

`Size Attribute property`	`Size Attribute function`	`NSLayoutConstraint.Attribute`
`dw.width`	`dw.make().width()`	`.width`
`dw.height`	`dw.make().height()`	`.height`

Relation & Multiplier & Priority

Relation & Priority are available in X-axis Attribute function & Y-axis Attribute function:

view.dw.make().left(100, by: .greaterThanOrEqual, priority: .defaultLow)

Relation & Multiplier & Priority are available in Size Attribute function:

view.dw.make().width(100, by: .greaterThanOrEqual, multiply: 2, priority: .required)

Relation: default is .equal
Multiplier: default is 1
Priority: default is .required

dw.make()

As you see above, you can use dw.make() to make full constraints easily.

dw.update()

You can use dw.update() to updating constant and priority value of a constraint.

view1.dw.update().top(200)

view2.dw.update().left(100, priority: .required)

dw.remake()

dw.remake() is similar to dw.make(), but will first remove all existing constraints installed by Driftwood.

view.dw.remake().left(20).top(30).width(20).height(10)

dw.remove()

You can use dw.remove() to removing any existing constraints installed by Driftwood.

view.dw.remove().left().top()

LayoutGuide

Driftwood can works with LayoutGuide easily.

let guide = UILayoutGuide()
superview.addLayoutGuide(guide)
guide.dw.make().left(10).top(10).height(10).width(10)

let box = UIView()
superview.addSubview(box)
box.dw.make().top(0, to: guide.dw.bottom).left(0).right(0).height(10)

Cache

All constraints installed by Driftwood will be cached for future reuse.

Debug

You can labeled with a name to any View or LayoutGuide for debug.

view.dw.make(labeled: "MyView").left(0).left(0)

It will be logs like this:

<Driftwood.@ViewController.swift#23.[make.left].(UIView`MyView`:0x00007fc636525da0)>: Duplicated constraint.

If resulting Unable to simultaneously satisfy constraints, it will be logs like this for each constraint installed by Driftwood:

<Driftwood.@ViewController.swift#23.[make.left].(UIView`MyView`:0x00007fc636525da0.left == UIView:0x00007fc636525111.right)>

NOTE: In release, Driftwood will not log debug info.

Demo

You can download this repo to see more usage.

Author

wlgemini, wangluguang@live.com