Extremely Fast views layouting without auto layout. No magic, pure code, full control and blazing fast. Concise syntax, intuitive, readable & chainable.

"No auto-layout constraints attached"

• PinLayout principles and philosophy

• Performance

• Documentation

  • Layout using distances from superview’s edges
  • Anchors
  • Edges
  • Relative positionning
  • Width, height and size
  • Margins
  • Warnings
  • More examples

• Installation

• FAQ

• Comments, ideas, suggestions, issues, ....

• Manual layouting (doesn't rely on auto layout).

• Blazing fast. PinLayout exist to be simple and fast as possible! In fact it is fast as manual layouting. See performance results below.

• Layout one view at a time.

• Concise syntax. Layout most views using a single line.

• Stateless

  • PinLayout doesn’t add any stored properties to UIViews. It simply computes the UIView.frame property, one view at a time.
  • Since it is stateless, it can be used with any other layout framework without conflicts. Each view can use the layout system that better suit it (PinLayout, constraints, flexbox, grids, …) A view can be layouted using PinLayout and later with another method/framework.

• No constraints/No auto-layout

  • Constraints are verbose and hard for a human brains to understand when there are many views implicated, even with sugar-syntax frameworks.
  • PinLayout positions views as a designer would explain it (eg: “The TextField is below the Label, aligned left, and is its width matches the other view’s width“).
  • No priorities, simply layout views in the order that makes sense. No priorities required.

• Before applying the new sets of attributes, PinLayout always start with the view’s current frame. So it’s possible to set the view’s size during the initialization (ex: view.pin.width(100).height(200)), and later only position the view (ex: view.pin.top(10).left(20)). This makes PinLayout really animation friendly.

• Not too intrusive. PinLayout only adds three properties to existing iOS classes: UIView.pin, UIView.anchor and UIView.edge

• Minimize as much as possible calculations and constants when layouting views.

• Methods match as much as possible other layouting systems, including CSS, flexbox, reactive Flexbox, …

  • margin, marginHorizontal, marginVertical, marginTop, marginLeft, marginBottom, marginRight
  • top, left, bottom, right, width, height
  • As in CSS and flexbox, right and bottom coordinates are offset from container view's right and bottom edges.

• Shorter possible commands to layout views, but keeping english phrasing almost valid.

PinLayout's performance has been measured using the excellent LayoutKit benchmark. PinLayout has been added to this benchmark to compare its performance.

As you can see in the following chart, PinLayout's performance is as fast as manual layouting, and up to 12x faster than auto layout, and 16x faster than UIStackViews.

These results also means that PinLayout is by far faster than any layout frameworks that is built over auto layout.

More details and explanation of the benchmark

Tested on a iPhone 6S iOS 10.3.2

X axis in the number cells in a UICollectionView, and Y axis is the time in miliseconds to layout all cells.

This example layout an image, a UISegmentedControl and a label.

• Logo image:
  • Its size is set to 100x100
  • The logo is layouted below the UINavigationBar with a margin of 10 pixels all around.
• UISegmentedControl
  • Layout it at the right of the logo
  • Use the remaining horizontal space with a left and right margin of 20 pixels.
• UILabel
  • Layout the label below the UISegmentedControl with a top margin of 10 pixels.
  • Adjust the label's width to match the UISegmentedControl's width.
  • Adjust the label's height to fit its new width. (calls internally UILabel's sizeThatFits() method)

override func layoutSubviews() {
   super.layoutSubviews() 
    
   logo.pin.topLeft().size(100).margin(74, 10, 10)
   segmented.pin.right(of: logo, aligned: .top).right().marginHorizontal(20)
   textLabel.pin.below(of: segmented, aligned: .left).width(of: segmented).pinEdges().marginTop(10).sizeToFit()
}

📌 This example and some other examples are available in the Example project. Please note that you must do a pod install before running the example project.

📌 PinLayout doesn't use auto layout constraints, it is a framework that manually layout views. For that reason you need to update the layout inside either UIView.layoutSubviews() or UIViewController.viewDidLayoutSubviews() to handle container size's changes, including device rotation. You'll also need to handle UITraitCollection changes for app's that support multitask. In the example above PinLayout's commands are inside UIView's layoutSubviews() method.

PinLayout can position a view’s edge relative to its superview edges.

Methods:

• top(_ value: CGFloat)
  The value specifies the top edge distance from the superview's top edge in pixels.
• top(_ percent: Percent)
  The value specifies the top edge distance from the superview's top edge in percentage of its superview's height.
• left(_ value: CGFloat)
  The value specifies the left edge distance from the superview's left edge in pixels.
• left(_ percent: Percent)
  The value specifies the left edge distance from the superview's left edge in percentage of its superview's width.
• bottom(_ value: CGFloat)
  The value specifies the bottom edge distance from the superview's bottom edge in pixels.
• bottom(_ percent: Percent)
  The value specifies the bottom edge distance from the superview's bottom edge in percentage of its superview's height.
• right(_ value: CGFloat)
  The value specifies the right edge distance from the superview's right edge in pixels.
• right(_ percent: Percent)
  The value specifies the right edge distance from the superview's right edge in percentage of its superview's width.
• hCenter(_ value: CGFloat)
  The value specifies the horizontal center distance from the superview's left edge in pixels.
• hCenter(_ percent: Percent)
  The value specifies the horizontal center distance from the superview's left edge in percentage of its superview's width.
• vCenter(_ value: CGFloat)
  The value specifies the vertical center distance from the superview's top edge in pixels.
• vCenter(_ percent: Percent)
  The value specifies the vertical center distance from the superview's top edge in percentage of its superview's height.

    view.pin.top(20).left(20)
    view.pin.top(25%).hCenter(0)
    view.pin.left(12).vCenter(100)

This example layout the view A to fit its superview frame with a margin of 10 pixels. It pins the top, left, bottom and right edges.

    viewA.pin.top(10).left(10).bottom(10).right(10)

Another possible solution using other PinLayout's methods (more details later):

    view.pin.topLeft().bottomRight().margin(10)

PinLayout also has shorter version that pins a view’s edge directly on its superview's corresponding edge.

Methods:

• top()
  Position the view top edge directly on its superview top edge. Similar to calling top(0).
• left()
  Position the view left edge directly on its superview top edge. Similar to calling left(0).
• bottom()
  Position the view bottom edge directly on its superview top edge. Similar to calling bottom(0).
• right()
  Position the view right edge directly on its superview top edge. Similar to calling right(0).
• hCenter()
  Position the view horizontal center directly on its superview horizontal center. Similar to calling hCenter(superview.frame.width / 2).
• vCenter()
  Position the view vertical center directly on its superview vertical center. Similar to calling hCenter(superview.frame.height / 2).

	view.pin.top().left()
	view.pin.bottom().right()
	view.pin.hCenter().vCenter()

This example is similar to the previous example, but pins edges directly on superview’s edges. It will layout the view A to fit its superview frame with a margin of 10 pixels.

    viewA.pin.top().left().bottom().right().margin(10)

PinLayout add anchors properties to UIViews. These properties are used to reference other view’s anchors.

PinLayout UIView’s anchors:

• UIView.anchor.topLeft
• UIView.anchor.topCenter
• UIView.anchor.topRight
• UIView.anchor.leftCenter
• UIView.anchor.centers
• UIView.anchor.rightCenter
• UIView.anchor.bottomLeft
• UIView.anchor.bottomCenter
• UIView.anchor.bottomRight

PinLayout can use anchors to position view’s related to other views.

Following methods position the corresponding view anchor on another view’s anchor.

Methods:

• topLeft(to anchor: Anchor)
• topCenter(to anchor: Anchor)
• topRight(to anchor: Anchor)
• leftCenter(to anchor: Anchor)
• center(to anchor: Anchor)
• rightCenter(to anchor: Anchor)
• bottomLeft(to anchor: Anchor)
• bottomCenter(to anchor: Anchor)
• bottomRight(to anchor: Anchor)

📌 These methods can pin a view’s anchor to any other view's anchor, even if don't have the same direct superview! It works with any views that have at some point the same ancestor.

    view.pin.topCenter(to: view1.anchor.bottomCenter)
    view.pin.topLeft(to: view1.anchor.topLeft).bottomRight(to: view1.anchor.center)

Layout using an anchors. This example pins the view B topLeft anchor on the view A topRight anchor.

	viewB.pin.topLeft(to: viewA.anchor.topRight)

Layout using multiple anchors.

It is also possible to combine two anchors to pin the position and the size of a view. The following example will position the view C between the view A and B with horizontal margins of 10px.

	viewC.pin.topLeft(to: viewA.anchor.topRight)
	         .bottomRight(to: viewB.anchor.bottomLeft).marginHorizontal(10)

PinLayout also has a shorter version that pins a view's anchor directly on its corresponding superview’s anchor.

The following methods position the corresponding view's anchor on another view’s anchor.

Methods:

• topLeft()
• topCenter()
• topRight()
• leftCenter()
• center()
• rightCenter()
• bottomLeft()
• bottomCenter()
• bottomRight()

For example .topRight() will pin the view’s topRight anchor on its superview’s topRight anchor..

	viewA.pin.topRight()

This is equivalent to:

	viewA.pin.topRight(to: superview.pin.topRight)

PinLayout adds edges properties to UIViews. These properties are used to reference other view’s edges.

PinLayout UIView’s edges:

• UIView.edge.top
• UIView.edge.left
• UIView.edge.bottom
• UIView.edge.right

PinLayout has methods to attach a UIView's edge (top, left, bottom or right edge) to another view’s edge.

Methods:

• top(to edge: VerticalEdge)
• left(to: edge: HorizontalEdge)
• bottom(to edge: VerticalEdge)
• right(to: edge: HorizontalEdge)

📌 These methods can pin a view’s edge to any other view's edge, even if don't have the same direct superview! It works with any views that have at some point the same ancestor.

	view.pin.left(to: view1.edge.right)
	view.pin.left(to: view1.edge.right).top(to: view2.edge.right)

Layout using an edge.

The following example will layout the view B left edge on the view A right edge. It only change the view B left coordinate

	viewB.pin.left(to: viewA.edge.right)

PinLayout also has methods to position relative to another view. This is similar to pinning to an edge with a slightly different syntax.

Methods:

• above(of UIView)
  Position the view above the specified view. This method is similar to pinning the view’s bottom edge.
• below(of UIView)
  Position the view below the specified view. This method is similar to pinning the view’s top edge.
• left(of UIView)
  Position the view left of the specified view. This method is similar to pinning the view’s right edge.
• right(of UIView)
  Position the view right of the specified view. This method is similar to pinning the view’s left edge.

📌 These methods can pin a view’s relative to any views, even if don't have the same direct superview! It works with any views that have at some point the same ancestor.

	view.pin.above(of: view2)
	view.pin.left(of: view2, aligned: .top)
	view.pin.left(of: view1).above(of: view2).below(of: view3).right(of: view4)

The following example will position the view C between the view A and B with margins of 10px using relative positioning methods.

	viewC.pin.top().left(of: viewA).right(of: viewB).margin(10)

This is an equivalent solution using edges:

	viewC.pin.top().left(to: viewA.edge.right).right(to: viewB.edge.left).margin(10)

This is also an equivalent solution using relative positioning and alignment explained in the next section:

	viewC.pin.left(of: viewA, aligned: .top).right(of: viewB, aligned: top).marginHorizontal(10)

PinLayout also has methods to position relative to another view but with also the ability of specifying the alignment. This is similar to pinning to an anchor with a more natural syntax.

Methods:

• above(of UIView, aligned: HorizontalAlignment)
• below(of UIView, aligned: HorizontalAlignment)
• left(of UIView, aligned: VerticalAlignment)
• right(of UIView, aligned: VerticalAlignment)

	view.pin.above(of: view2, aligned: .left)
	view.pin.above(of: view2, aligned: .right)
	view.pin.left(of: view2, aligned: .top)

The following example layout the view B below the view A aligned on its center.

	viewB.pin.below(of: viewA, aligned: .center)

This is an equivalent solutions using anchors:

	viewB.pin.topCenter(to: viewA.anchor.bottomCenter)

PinLayout has methods to set the view’s height and width.

Methods:

• width(_ width: CGFloat)
  The value specifies the width of the view in pixels. Value must be non-negative.

• width(percent: Percent)
  The value specifies the width of the view in percentage of its superview. Value must be non-negative.

• width(of view: UIView)
  Set the view’s width to match the referenced view’s width.

• height(_ height: CGFloat)
  The value specifies the height of the view in pixels.

• height(percent: Percent)
  The value specifies the height of the view in percentage of its superview. Value must be non-negative.

• height(of view: UIView)
  Set the view’s height to match the referenced view’s height

• size(_ size: CGSize)
  The value specifies the size (width and value) of the view in pixels. Values must be non-negative.

• size(_ percent: Percent)
  The value specifies the width and the height of the view in percentage of its superview. Values must be non-negative.

• size(_ sideLength: CGFloat)
  The value specifies the width and the height of the view in pixels, creating a square view. Values must be non-negative.

• size(of view: UIView)
  Set the view’s size to match the referenced view’s size

	view.pin.width(50%)
	view.pin.width(100)
	view.pin.width(of: view1)
	
	view.pin.height(100%)
	view.pin.height(200)
	
	view.pin.size(of: view1)
	view.pin.size(50%)
	view.pin.size(250)

PinLayout applies margins similar to CSS.

PinLayout has methods to apply margins.

Methods:

• marginTop(_ value: CGFloat)

• marginLeft(_ value: CGFloat)

• marginBottom(_ value: CGFloat)

• marginRight(_ value: CGFloat)

• marginHorizontal(_ value: CGFloat)

• marginVertical(_ value: CGFloat)

• margin(_ value: CGFloat)

• margin(_ vertical: CGFloat, _ horizontal: CGFloat)

• margin(_ top: CGFloat, _ horizontal: CGFloat, _ bottom: CGFloat)

• margin(_ top: CGFloat, _ left: CGFloat, _ bottom: CGFloat, _ right: CGFloat)

• pinEdges()

	view.pin.topLeft().margin(20)
	view.pin.bottom().marginBottom(20)
	view.pin.left().right().marginHorizontal(20)
	view.pin.topLeft().bottomRight().margin(10, 12, 0, 12)

The following section explains how CSS/PinLayout margin rules are applied.

This table explains how and when left and right margins are applied depending on which view’s attribute has been pinned using PinLayout.

NOTE: - indicates that the margin is not applied.

This table explains how and when top and bottom margins are applied depending on which view’s attribute has been pinned using PinLayout.

In this example, only the left margin is applied

	view.pin.left().margin(10)

In this example, only the right margin is applied

	view.pin.right().width(100).marginHorizontal(10)

In this example, the left and right margins are applied

	view.pin.left().right().margin(10)

In this example, left, right and top margins are applied. Note that the view’s width has been reduced to apply left and right margins.

	view.pin.topLeft().right().height(100).margin(10)

In this example, left, right, top and bottom margins are applied.

	view.pin.topLeft().bottomRight().margin(10)

The pinEdges() method pins the four edges (top, left, bottom and right edges) before applying margins.

This method is useful in situations where the width and/or the height attributes have been pinned. This method is an add-on, there is no equivalent in CSS.

Without pinEdges() margins rules would be applied and the view would be moved to the left.

	view.pin.left().width(percent: 100).marginHorizontal(20)

With pinEdges() the left and right margins are applied even if only the left and width has been set. The reason is the call to pinEdges() has pinned the two horizontal edges at their position before applying margins.

	view.pin.left().width(percent: 100).pinEdges().marginHorizontal(20)

NOTE: In that in that particular situation, the same results could have been achieved differently too:

	view.pin.left().right().marginHorizontal(20)

In debug, PinLayout will display warnings when pin rules cannot be applied.

Warning reasons

• The newly pinned attributes conflict with other already pinned attributes.
  Example:
  view.pin.left(10).right(10).width(200)
  👉 Layout Conflict: width(200) won't be applied since it conflicts with the following already set properties: left: 0, right: 10.

• The newly pinned attributes have already been set to another value.
  Example:
  view.pin.width(100).width(200)
  👉 Layout Conflict: width(200) won't be applied since it value has already been set to 100.

• The view being layout hasn’t been added yet into a superview
  Example:
  view.pin.width(100)
  👉 Layout Warning: width(100) won't be applied, the view must be added as a sub-view before being layouted using this method.

• A view is used as a reference, either directly or using its anchors or its edges, but hasn’t been added yet to a superview.
  Example:
  view.pin.left(of: view2)
  👉 Layout Warning: left(of: view2) won't be applied, the view must be added as a sub-view before being used as a reference.

• The width and the height must be non negative values.
  Example:
  view.pin.width(-100)
  👉 Layout Warning: The width (-100) must be greater or equal to 0.

width and/or height cannot be determined using current PinLaoyout's commands

size(...)'s height won't be aplied... size(...)'s widht won't be applied....

Warnings can be disabled in debug mode too by setting the boolean PinLayoutLogConflicts to false.

• You should always specifies methods in the same order, it makes layout lines easier to understand. Here is our prefered ordering:
  view.pin.[EDGE|ANCHOR|RELATIVE].[WIDTH|HEIGHT|SIZE].[pinEdges()].[MARGINS].[sizeToFit()]

  This order reflect the logic inside PinLayout. pinEdges() is applied before margins and margins are applied before sizeToFit().

   view.pin.top().left(10%).margin(10, 12, 10, 12)
   view.pin.left().width(100%).pinEdges().marginHorizontal(12)
   view.pin.left().right().margin(0, 12).sizeToFit()
   view.pin.width(100).height(100%)

• If the layout line is too long, you can split in multiple lines:

   textLabel.pin.below(of: titleLabel)
      .right(of: statusIcon).left(of: accessoryView)
      .above(of: button).marginHorizontal(10)
  

The following examples show how PinLayout can be used to adjust views size and position to the size of their container. in this case containers are cells.

Cell A:

• A1 is left aligned with a width of 50px
• A2 fills the remaining space

	a1.pin.topLeft().bottom().width(50)
	a2.pin.right(of: a1, aligned: .top).bottomRight().marginLeft(10)

Cell B:

• B2 is right aligned with a fixed width of 50px
• B1 fills the remaining space

	b2.pin.topRight().bottom().width(50)
	b1.pin.left(of: b2, aligned: .top).bottomLeft().marginRight(10)

Cell C:

• C2 is centered with a fixed width of 50px
• C1 fills the remaining left space
• C3 fills the remaining right space

	c2.pin.topCenter().width(50).bottom()
	c1.pin.left(of: c1, aligned: .top).bottomLeft().marginRight(10)
	c3.pin.right(of: c2, aligned: .top).bottomRight().marginLeft(10)

Cell D:

• D1 takes 25% of its container width
• D2 takes 50% of its container width
• D3 fills the remaining space

	d1.pin.topLeft().bottom().width(25%)
	d2.pin.right(of: d1, aligned: .top).bottom().width(50%).marginLeft(10)
	d3.pin.right(of: d2, aligned: .top).bottomRight().marginLeft(10)

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

    pod 'PinLayout'

Then, run pod install.

To integrate PinLayout into your Xcode project using Carthage, specify it in your Cartfile:

github "mirego/PinLayout"

Then, run carthage update to build the framework and drag the built PinLayout.framework into your Xcode project.

Once you have your Swift package set up, you only need to add PinLayout as a dependency of your Package.swift.

dependencies: [
    .Package(url: "https://github.com/mirego/PinLayout.git", majorVersion: 1)
]

• minWidth/maxWidth, minHeight/maxHeight
• CALayer support
• ...

• Q: When the device rotation change, the layout is not updated.
  R: PinLayout doesn't use auto layout constraints, it is a framework that manually layout views. For that reason you need to update the layout inside either UIView.layoutSubviews() or UIViewController.viewDidLayoutSubviews() to handle container size's changes, including device rotation. You'll also need to handle UITraitCollection changes for app's that support multitask.

• Q: How to apply percentage from a CGFloat, a Float or a Int value?
  R: Many PinLayout's method has a parameter of type Percent. You can easily specify this type of parameter simply by adding the % operator to your value (eg: view.pin.left(10%).width(50%). It is similar if you have a value of type CGFloat, Float or Int, simply adds the % operator:

   let percentageValue: CGFloat = 50
   view.pin.width(percentageValue%)
  

For any comments, ideas, suggestions, issues, simply open an issue.

PinLayout was inspired by other great layout frameworks, including:

• MCUIViewLayout
• HTML's CSS
• SnapKit
• Stevia
• ... and even Auto layout :-)

BSD 3-Clause License