Swift operators overloading and autolayout

LayoutConstraint.swift

//
//  LayoutConstraint.swift
//  SwiftControls
//

import UIKit

struct LayoutAttribute
{
  var view:UIView?
  var attribute:NSLayoutAttribute
  var multiplier:CGFloat
  var constant:CGFloat
  
  init(view:UIView, attribute: NSLayoutAttribute, constant:CGFloat = 0, multiplier:CGFloat = 1.0){
    self.view = view;
    self.attribute = attribute
    self.multiplier = multiplier
    self.constant = constant;
  }
  
  init(_ constant:CGFloat){
    self.attribute = .NotAnAttribute
    self.multiplier = 1
    self.constant = constant;
  }
}

func == (left: LayoutAttribute, right: LayoutAttribute) -> NSLayoutConstraint {
  var layoutConstraint = NSLayoutConstraint(item:left.view!,
    attribute: left.attribute, relatedBy: NSLayoutRelation.Equal, toItem: right.view,
    attribute: right.attribute, multiplier: right.multiplier, constant: right.constant)
  
  return layoutConstraint
}

func >= (left: LayoutAttribute, right: LayoutAttribute) -> NSLayoutConstraint {
  var layoutConstraint = NSLayoutConstraint(item: left.view!,
    attribute: left.attribute, relatedBy: NSLayoutRelation.GreaterThanOrEqual, toItem: right.view, attribute: right.attribute,
    multiplier: right.multiplier, constant: right.constant);
  return layoutConstraint
}

func <= (left: LayoutAttribute, right: LayoutAttribute) -> NSLayoutConstraint {
  var layoutConstraint = NSLayoutConstraint(item: left.view!,
    attribute: left.attribute, relatedBy: NSLayoutRelation.LessThanOrEqual, toItem: right.view, attribute: right.attribute,
    multiplier: right.multiplier, constant: right.constant);
  return layoutConstraint
}

func == (left: LayoutAttribute, right: CGFloat) -> NSLayoutConstraint {
  var layoutConstraint = NSLayoutConstraint(item:left.view!,
    attribute: left.attribute, relatedBy: NSLayoutRelation.Equal, toItem: nil,
    attribute: .NotAnAttribute, multiplier: 1.0, constant: right)
  
  return layoutConstraint
}

func <= (left: LayoutAttribute, right: CGFloat) -> NSLayoutConstraint {
  var layoutConstraint = NSLayoutConstraint(item:left.view!,
    attribute: left.attribute, relatedBy: NSLayoutRelation.LessThanOrEqual, toItem: nil,
    attribute: .NotAnAttribute, multiplier: 1.0, constant: right)
  
  return layoutConstraint
}

func >= (left: LayoutAttribute, right: CGFloat) -> NSLayoutConstraint {
  var layoutConstraint = NSLayoutConstraint(item:left.view!,
    attribute: left.attribute, relatedBy: NSLayoutRelation.GreaterThanOrEqual, toItem: nil,
    attribute: .NotAnAttribute, multiplier: 1.0, constant: right)
  
  return layoutConstraint
}

func *(left: LayoutAttribute, right: (CGFloat, CGFloat)) -> LayoutAttribute {
  var layoutAttribute = LayoutAttribute(view:left.view!, attribute: left.attribute, constant: right.0, multiplier:right.1)
  return layoutAttribute
}

func +(left: LayoutAttribute, right: CGFloat) -> LayoutAttribute {
  var layoutAttribute = LayoutAttribute(view:left.view!, attribute: left.attribute, constant: right, multiplier:1.0)
  return layoutAttribute
}

func -(left: LayoutAttribute, right: CGFloat) -> LayoutAttribute {
  var layoutAttribute = LayoutAttribute(view:left.view!, attribute: left.attribute, constant: -right, multiplier:1.0)
  return layoutAttribute
}

extension UIView
{
  func addConstraints (constraints: NSLayoutConstraint...){
    for constraint in constraints {
      self.addConstraint(constraint)
    }
  }
  
  var width : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .Width); }
  }
  
  var height : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .Height); }
  }

  var leading : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .Leading); }
  }

  var trailing : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .Trailing); }
  }

  var top : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .Top); }
  }
  
  var bottom : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .Bottom); }
  }
 
  var centerX : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .CenterX); }
  }

  var centerY : LayoutAttribute {
    get { return LayoutAttribute(view: self, attribute : .CenterY); }
  }
}