Align image vertically in Swift 3

Question

I am trying to vertically align a image in swift 3, but the following code is not working, I don't know why?

addConstraint(NSLayoutConstraint(item: iconImageView, attribute: .centerY, relatedBy: .equal, toItem: self, attribute: .centerY, multiplier: 1, constant: 0))

Any ideas?

Answer 1

The code above was fine but it was the following code that I changed:

From

addConstraintsWithFormat(format:"V:|[v0(30)]|", views: iconImageView)

To

addConstraintsWithFormat(format:"V:[v0(30)]", views: iconImageView)

Works fine now