Getting an existing NSLayoutConstraint for the width?

Question

I\'m trying to animate a control in Cocoa with auto layout.

Now, I can set [[constraint animator] setConstant:newWidth];, which works. But how can I get the

Answer 1

Here is the swift 3 version tested on Xcode 8.2.1 and macOS 10.12.2.

The code shows how to get a button's width and height constraints, but you could filter whatever you want from NSLayoutAttribute enum.

let cons = signInButton.constraints.filter {
    $0.firstAttribute == NSLayoutAttribute.width || $0.firstAttribute == NSLayoutAttribute.height /// or other from `NSLayoutAttribute`
}
// do something with the constraints array, e.g.
NSLayoutConstraint.deactivate(cons)