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Carthage compatible Pod version Pod Platform Build Status

Dixi is a collection of Swift operators for creating autolayout constraints inspired by Apple's visual format language.

Why use Dixi?

The iOS/OS X SDK provides two methods of constructing constraints from code: by explicitly configuring the constraint parameters or with the aid of the visual format language. The first option offers the full power of the API but is the most tedious to write. The second option covers most commonly used functionality and is simpler to write. However, since it's string based, the specifiers are only evaluated at runtime, letting potential errors slip through.

Dixi offers all the functionality of the visual format language, except writing multiple constraints at the same time. Since no strings are used the constraints syntax is evaluated early, at build time. Views and constants can be used directly in constraints, eliminating the need of defining dictionaries for parameters.

Requirements

  • Swift 1.2 (Xcode 6.3)
  • iOS 8.0 or OS X 10.9

Installing

Install with Carthage

Drop this line in your Cartfile:

github "MihaiDamian/Dixi" ~> 0.1

Install with CocoaPods

Drop this line in your Podfile:

pod 'Dixi', '~> 0.1'

Using Dixi

Dixi allows you to create autolayout constraints using a concise and type safe notation with the aid of some custom operators. The syntax is designed to resemble Apple's visual format language, though there are some differences.

Here's how to create a constraint that defines a 10 points horizontal distance between two views:

let horizontalDistanceConstraint = view1 |- 10 -| view2

ca Dixi operators create LayoutConstraint objects that can be transformed into NSLayoutConstraint objects or added directly to views:

superview.addConstraint(horizontalDistanceConstraint)

Unlike in visual format language where you can define multiple constraints with a single string, with Dixi you can only create constraints one at a time. Writing this is not valid and the compiler will complain:

let constraints = view1 |- 10 -| view2 |- 15 -| view3

Instead you can write the code above as:

let constraints = [view1 |- 10 -| view2, view2 |- 15 -| view3]

By default Dixi operators construct constraints on the horizontal axis (widths, leading & trailing spacing). You can construct constraints on the vertical axis (heights, top & bottom spacing) by prefixing any LayoutConstraint with the vertical axis operator:

let heightGreaterThanConstraint = ^(view1 >= 50)

You can also use the horizontal axis operator if you want to make things explicit:

let explicitAxisConstraint = >(view1 >= 50)

Check out the Demo playground for more examples of Dixi in action.

Complete list of operators

Operator Name Example 
  •   |Standard spacing between views|view1 - view2

|- |Trailing space to view|view |- 10 -| |Leading space to view|10 -| view || |Flush views|view1 || view2

= |Width/height greater or equal than|view >= 50 <= |Width/height smaller or equal than|view <= 50 == |Width/height equal to|view1 == view2 |-| |Leading/trailing/top/bottom distance to superview|10 |-| view ~ |Priority|(view >= 50) ~ 20 ^ |Vertical axis|^(view == 10) |Horizontal axis|>(view == 10)

License

Dixi is licensed under MIT license.