layout.swift

self.navigationController.view.addConstraints([
    NSLayoutConstraint(
        item: add,
        attribute: .Width,
        relatedBy: .Equal,
        toItem: add,
        attribute: .Width,
        multiplier: 1,
        constant: 0
    ),
    NSLayoutConstraint(
        item: add,
        attribute: .Height,
        relatedBy: .Equal,
        toItem: add,
        attribute: .Height,
        multiplier: 1,
        constant: 0
    ),
    NSLayoutConstraint(
        item: add,
        attribute: .Right,
        relatedBy: .Equal,
        toItem: navigationBar,
        attribute: .Right,
        multiplier: 1,
        constant: 0
    ),
    NSLayoutConstraint(
        item: add,
        attribute: .CenterY,
        relatedBy: .Equal,
        toItem: navigationBar,
        attribute: .CenterY,
        multiplier: 1,
        constant: 0
    )
])