Cannot convert value of type '[NSLayoutConstraint]' error in swift 2

Question

I want to add constraint to the UIImageView by adding this line of code:

addConstraint(NSLayoutConstraint.constraintsWithVisualFormat("H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": userProfileImageView]))

But xcode show me this error:

How I can fix this error?

Answer 1

Use addConstraints, instead of addConstraint. constraintsWithVisualFormat returns an array.

Your code becomes:

addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[v0]|", options: [], metrics: nil, views: ["v0": userProfileImageView])

Answer 2

let horizontalprofileViewConstraint = NSLayoutConstraint.constraintsWithVisualFormat("H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": userProfileImageView]

If you click option and hover over horizontalprofileViewConstraint you will see its type as [NSLayoutConstraint] which is already an array.

So what you can do is:

view.addConstraints(horizontalprofileViewConstraint)

if you have more than one view then you cand do:

view.addConstraints(horizontalprofileViewConstraint + verticalprofileViewConstraint)

The + joins to arrays for you.