Swift UIStackView: Positioning elements from center programmatically

Question

I am trying to get elements inside a UIStackView to position themselves equally from the center.

This is the desired effect I would like:

As you can see, I would like the two text fields to be equally spaced from each other and aligned center within the stack view.

This stack view will have either 1 - 7 textfields that I need lined up.

Here is what is currently coming out:

This is how I am setting the Text Fields

let textLabel = UILabel()
textLabel.backgroundColor = UIColor.red
textLabel.widthAnchor.constraint(equalToConstant: 40.0).isActive = true
textLabel.heightAnchor.constraint(equalToConstant: 20.0).isActive = true
textLabel.text  = "Hi"
textLabel.textAlignment = .center

let textLabel1 = UILabel()
textLabel1.backgroundColor = UIColor.red
textLabel1.widthAnchor.constraint(equalToConstant: 40.0).isActive = true
textLabel1.heightAnchor.constraint(equalToConstant: 20.0).isActive = true
textLabel1.text  = "Hi"
textLabel1.textAlignment = .center

I am generating the stack view like so:

//Stack View
let stackView   = UIStackView()
stackView.axis  = UILayoutConstraintAxis.horizontal
stackView.distribution  = UIStackViewDistribution.equalCentering
stackView.alignment = UIStackViewAlignment.fill
stackView.spacing   = 16.0

stackView.addArrangedSubview(textLabel)
stackView.addArrangedSubview(textLabel1)
stackView.translatesAutoresizingMaskIntoConstraints = false;

self.view.addSubview(stackView)

//Constraints

stackView.leftAnchor.constraint(equalTo: self.view.leftAnchor, constant: 50).isActive = true
stackView.rightAnchor.constraint(equalTo: self.view.rightAnchor, constant: -50).isActive = true
stackView.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100).isActive = true

How do I get the elements inside to align center?

I thought it was

UIStackViewDistribution.equalCentering

However, that didn't do much.

Solution

Thats odd. Normally a horizontal UIStackView with center alignment and equal centering distribution should do exactly that:

But maybe I'm not understanding you correct and you actually want something like this:

In which case you have to chose Fill Equally as the distribution method and make the labels itself center their text:

Comments

[Norman]

I have found Interface Builder to show stale values for stack alignments and distributions, you might try restarting Xcode and see if it renders differently.

[xxtesaxx]

I don't know what you mean, nor have I had problems with stackviews in IB. :/

[xxtesaxx]

This was just a visual demo of the stackview modes.

[Norman]

It's a really clear and helpful answer. I have experienced Interface Builder occasionally not reflecting the current alignment or distribution setting on the visual representation of the storyboard.

[xxtesaxx]

Ah i see. What usually could help as well is change the device orientation in the storyboard or resize the view if it is free-forming.