PinLayout

Swift manual views layouting, no magic, pure code, full control. Concise syntax, readable & chainable.

"No auto-layout constraints attached"

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

PinLayout principles and philosophy

• Manual layouting. No magic, pure code, full control.

• Layout one view at a time.

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

• Stateless

  • The layout system doesn’t add any stored properties to UIViews. It simply compute 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, constraint, 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 match the other view’s width“).
  • No priorities, simply layout views in the order that make sense. No priority 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.

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

• Methods matches as much as possible other layouting system, 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’s view right and bottom edges.

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

Installation

CocoaPods

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

    pod 'PinLayout'

Then, run pod install.

Carthage

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.

Documentation

Layout using distances from superview’s edges

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.

Usage Examples:

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

Example:

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)

Layout directly on superview’s edges

PinLayout also have shorten version that pin a view’s edge directly on its superview 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(0).
• vCenter()
  Position the view vertical center directly on its superview vertical center. Similar to calling vCenter(0).

Usage examples:

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

Example:

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

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

Anchors

PinLayout UIView’s anchors

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

---

Layout using anchors

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)

NOTE: These methods can also pin a view’s anchor to another view that is not a direct sibling. It works with any views that have at some point the same ancestor.

Usage examples:

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

Example:

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)

Example:

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 an horizontal margins of 10px.

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

---

Layout using superview’s anchors

PinLayout also have shorten version that pin a view's anchor directly on its corresponding superview’s anchor.

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

Methods:

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

Example:

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)

Edges

PinLayout UIView’s edges

PinLayout add 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

---

Layout using edges

PinLayout have 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)

Usage examples:

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

Example:

Layout using an edge.

The following example 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)

Relative positionning

Layout using edges relative positioning

PinLayout also have method to position relative to another view. This is similar to pinning to an edge with a slittly 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.

Usage examples:

	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)

Example:

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 solutions using edges:

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

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

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

Layout using relative positioning and alignment

PinLayout also have method 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)

Usage examples:

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

Example:

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)

Width, height and size

Adjust view width, height and size

PinLayout have 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

• sizeToFit()

Usage examples:

	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)

sizeToFit()

sizeToFit() is the equivalent of calling sizeThatFits() on the size of the view once PinLayout has computed the size and have applied margins.

Usage examples:

	label.pin.width(200).sizeToFit()

Example:

The following example layout the UILabel on the right side of the UIImageView with a margin of 10px all around and also adjust the UILabel’t height to fit the text size. Note on the result that the UILabel’s height has changed to fit its content.

	label.pin.right(of: image, aligned: .top).right().marginHorizontal(10).sizeToFit()

Margins

PinLayout applies margins similar to CSS.

PinLayout's margins

PinLayout have methods to apply margin.

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()

Usage examples:

	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)

PinLayout margin rules

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

When and how horizontal margins are applies in PinLayout?

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

View’s pinned attributes	Left Margin	Right Margin
Left	Move view right	-
Left and Width	Move view right	-
Right	-	Move view left
Right and Width	-	Move view left
Left and Right	Reduce the width to apply the left margin	Reduce the width to apply the right margin

NOTE: - indicates that the margin is not applied.

When and how does vertical margins are applies in PinLayout?

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

View’s pinned attributes	Left Margin	Right Margin
Top	Move view down	-
Top and Height	Move view down	-
Bottom	-	Move view up
Bottom and Height	-	Move view up
Top and Bottom	Reduce the height to apply the top margin	Reduce the height to apply the bottom margin

Margin examples

Example 1:

In this example, only the left margin is applied

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

Example 2:

In this example, only the right margin is applied

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

Example 3:

In this example, the left and right margins are applied

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

Example 4:

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

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

Example 5:

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

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

pinEdges()

The pinEdges() method pin 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 a add-on, there is no equivalent in CSS.

Example without pinEdges

Without pinEdges() margins rules has been applied and has moved the view to the left.

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

Example with pinEdges

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() have 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)

Warnings

PinLayout's warnings

In debug, PinLayout will displays warning 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 was already 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.

Disabling warning

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

More examples

Adjust to container size

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 fill 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 fill 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 fill the remaining left space
• C3 fill 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 fill 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)

Contributing

1. Fork it!
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes: git commit -am 'Add some feature'
4. Push to the branch: git push origin my-new-feature
5. Submit a pull request :D

History

TODO

Credits

TODO

License

BSD 3-Clause License