Latest 4.0.0
Homepage https://github.com/Skyvive/Swiftstraints
License MIT
Platforms ios 8.0, tvos 9.0, requires ARC
Authors

Swiftstraints can turn verbose auto-layout code:

let constraint = NSLayoutConstraint(item: blueView,
                               attribute: NSLayoutAttribute.Width,
                               relatedBy: NSLayoutRelation.Equal,
                                  toItem: redView,
                               attribute: NSLayoutAttribute.Width,
                              multiplier: 1.0,
                                constant: 0.0)

Into one just one line of code:

let constraint = blueView.widthAnchor == redView.widthAnchor

Or transform your less than consise visual format language code:

let constraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|[leftView]-10-[rightView]|",
                               options: NSLayoutFormatOptions(0),
                               metrics: nil,
                               views: ["leftView":leftView, "rightView":rightView])

Into the following:

let constraints = NSLayoutConstraints("H:|[(leftView)]-10-[(rightView)]|")

That was easy!

Installation

Swiftstraints is available through CocoaPods. To install, simply include the following lines in your podfile:

use_frameworks!
pod 'Swiftstraints'

Be sure to import the module at the top of your .swift files:

import Swiftstraints

Alternatively, clone this repo or download it as a zip and include the classes in your project.

Constraints

With Swiftstraints you can create constraints that look just Apple’s generic constraint definition:

item1.attribute1 = multiplier × item2.attribute2 + constant

Swifstraints utilizes the new layout anchors introduced in iOS 9:

let view = UIView()
view.widthAnchor
view.heightAnchor
view.trailingAnchor
view.centerXAnchor
etc...

Swiftstraints implements operator overloading so that you can easily create custom constraints:

let blueView = UIView()
let redView = UIView()
let constraint = blueView.heightAnchor == redView.heightAnchor

Just as you would expect, you can specify a multiplier:

let constraint = blueView.heightAnchor == 2.0 * redView.heightAnchor

Or add a constant:

let constraint = blueView.heightAnchor == redView.heightAnchor + 10.0

You can specify inequalities:

let constraint = blueView.heightAnchor <= redView.heightAnchor

And you can define constant constraints if you so choose:

let constraint = blueView.heightAnchor == 100.0

Swiftstraints can readily compute relatively complex constraints:

let constraint = blueView.heightAnchor * 1.4 - 5.0 >= redView.heightAnchor / 3.0 + 400

It’s really easy.

Visual Format Language

Apple provides an API that lets you create multiple constraints simultaneously with the Visual Format Language. As we saw before it can be a little cumbersome:

let constraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|[leftView]-10-[rightView]|",
                               options: NSLayoutFormatOptions(0),
                               metrics: nil,
                               views: ["leftView":leftView, "rightView":rightView])

Swiftstraints uses string interpolation to let you specify the same constraints in one line of code:

let constraints = NSLayoutConstraints("H:|[(leftView)]-10-[(rightView)]|")

Swiftstraints also extends UIView so that you can add constraints easily using the interpolated string format:

superview.addConstraints("H:|[(leftView)]-10-[(rightView)]|")

Super easy, super simple.

Revision History

  • 3.0.1 – Bug fixes and limited iOS 8 support (Thank you catjia1011)
  • 3.0.0 – Updated to Swift 3
  • 2.2.0 – Added support for UILayoutPriority
  • 2.1.0 – Fixed a view reference bug and added a new convenience method for adding constraints
  • 2.0.2 – Added support for tvOS target.
  • 2.0.1 – Updated to include support for axis anchors, increased test coverage and more documentation.
  • 2.0.0 – Updated for Swift 2.0 and iOS 9. Now uses layout anchors for simple constraints and string interpolation for Visual Format Language constraints.
  • 1.1.0 – Minor API tweaks
  • 1.0.0 – Initial Release

Author

Brad Hilton, [email protected]

License

Swiftstraints is available under the MIT license. See the LICENSE file for more info.

Latest podspec

{
    "name": "Swiftstraints",
    "version": "4.0.0",
    "summary": "Auto Layout Made Easy",
    "description": "Write auto layout constraints in a single line of code.",
    "homepage": "https://github.com/Skyvive/Swiftstraints",
    "license": {
        "type": "MIT",
        "file": "LICENSE"
    },
    "authors": {
        "Brad Hilton": "[email protected]"
    },
    "source": {
        "git": "https://github.com/Skyvive/Swiftstraints.git",
        "tag": "4.0.0"
    },
    "platforms": {
        "ios": "8.0",
        "tvos": "9.0"
    },
    "source_files": [
        "Swiftstraints",
        "Swiftstraints/**/*.{swift,h,m}"
    ],
    "requires_arc": true
}

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