NSLayoutAnchor+MultiplierConstraints

NSLayoutAnchor+MultiplierConstraints.swift

import UIKit

extension NSLayoutXAxisAnchor {
    func constraint(equalTo anchor: NSLayoutXAxisAnchor,
                    multiplier m: CGFloat,
                    constant c: CGFloat = 0.0) -> NSLayoutConstraint {
        let constraint = self.constraint(equalTo: anchor, constant: c)
        return constraint.constraint(multiplier: m)
    }

    func constraint(greaterThanOrEqualTo anchor: NSLayoutXAxisAnchor,
                    multiplier m: CGFloat,
                    constant c: CGFloat = 0.0) -> NSLayoutConstraint {
        let constraint = self.constraint(greaterThanOrEqualTo: anchor, constant: c)
        return constraint.constraint(multiplier: m)
    }

    func constraint(lessThanOrEqualTo anchor: NSLayoutXAxisAnchor,
                    multiplier m: CGFloat,
                    constant c: CGFloat = 0.0) -> NSLayoutConstraint {
        let constraint = self.constraint(lessThanOrEqualTo: anchor, constant: c)
        return constraint.constraint(multiplier: m)
    }
}

extension NSLayoutYAxisAnchor {
    func constraint(equalTo anchor: NSLayoutYAxisAnchor,
                    multiplier m: CGFloat,
                    constant c: CGFloat = 0.0) -> NSLayoutConstraint {
        let constraint = self.constraint(equalTo: anchor, constant: c)
        return constraint.constraint(multiplier: m)
    }

    func constraint(greaterThanOrEqualTo anchor: NSLayoutYAxisAnchor,
                    multiplier m: CGFloat,
                    constant c: CGFloat = 0.0) -> NSLayoutConstraint {
        let constraint = self.constraint(greaterThanOrEqualTo: anchor, constant: c)
        return constraint.constraint(multiplier: m)
    }

    func constraint(lessThanOrEqualTo anchor: NSLayoutYAxisAnchor,
                    multiplier m: CGFloat,
                    constant c: CGFloat = 0.0) -> NSLayoutConstraint {
        let constraint = self.constraint(lessThanOrEqualTo: anchor, constant: c)
        return constraint.constraint(multiplier: m)
    }
}

private extension NSLayoutConstraint {
    func constraint(multiplier: CGFloat) -> NSLayoutConstraint {
        return NSLayoutConstraint(item: firstItem!,
                                  attribute: firstAttribute,
                                  relatedBy: relation,
                                  toItem: secondItem,
                                  attribute: secondAttribute,
                                  multiplier: multiplier,
                                  constant: constant)
    }
}