Thank you! It seems like I was missing NSLayoutConstraint.activate([ previewView.topAnchor.constraint(equalTo: self.view.topAnchor), previewView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor), previewView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor), previewView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor) ]) in my code