iOS NSLayoutConstraint Fixed Width using constraintWithItem

Question

I\'d like to set a constraint to give a UIButton a fixed (constant) width programmatically. I know I can do this with constraintsWithVisualFormat, but I\'ve been using constrain

Answer 1

In swift:

let width = 120
let constraint = NSLayoutConstraint(
    item: myView,
    attribute: .width,
    relatedBy: .equal,
    toItem: nil,
    attribute: .notAnAttribute,
    multiplier: 1.0,
    constant: width)
NSLayoutConstraint.activateConstraints([constraint])

Then you can change constraint's constant value

constraint.constant = width * 2