Align UIImage vertically center - ios

Question

I am trying to align an image vertically central using Swift. I understand you do this by using constraints, however I've been unable to get this to work.
func getLogo() {
let logo = UIImage(named: "LogoWhite")
let logoView = UIImageView(image: logo)
logoView.contentMode = .scaleAspectFit
self.addSubview(logoView)
}

Answer 1

If you don't want to use constraints (I personally do not like them) you can check for container center and put your UIImageView there.
Example:
containerView -> the view that contains your logo
logo -> the view you want vertically centered
logo.center.y = containerView.center.y
If the containerView is the screen, then
let screen = UIScreen.main.bounds
let height = screen.height
logo.center.y = screen.height / 2

Answer 2

I would suggest using extensions on UIView to make auto layout much easier. This seems like a lot of code to begin with for such a simple task but these convenience functions will make things a lot quicker in the long run for example:
public func anchor(top: NSLayoutYAxisAnchor?, leading: NSLayoutXAxisAnchor?, bottom: NSLayoutYAxisAnchor?, trailing: NSLayoutXAxisAnchor?, padding: UIEdgeInsets = .zero, size: CGSize = .zero){
translatesAutoresizingMaskIntoConstraints = false
//Set top, left, bottom and right constraints
if let top = top {
topAnchor.constraint(equalTo: top, constant: padding.top).isActive = true
}
if let leading = leading {
leadingAnchor.constraint(equalTo: leading, constant: padding.left).isActive = true
}
if let bottom = bottom {
bottomAnchor.constraint(equalTo: bottom, constant: -padding.bottom).isActive = true
}
if let trailing = trailing {
trailingAnchor.constraint(equalTo: trailing, constant: -padding.right).isActive = true
}
//Set size contraints
if size.width != 0 {
widthAnchor.constraint(equalToConstant: size.width).isActive = true
}
if size.height != 0 {
heightAnchor.constraint(equalToConstant: size.height).isActive = true
}
}
Then you could simply call:
someUIView.anchor(anchor(top: topAnchor, leading: leadingAnchor, bottom: bottomAnchor, trailing: nil, padding: .init(top: 16, left: 16, bottom: 16, right: 16), size: .init(width: 80, height: 80))
Then to answer your question directly you could then add more extensions to do some stuff easily:
public func anchorCenterXToSuperview(constant: CGFloat = 0) {
translatesAutoresizingMaskIntoConstraints = false
if let anchor = superview?.centerXAnchor {
centerXAnchor.constraint(equalTo: anchor, constant: constant).isActive = true
}
}
Finally you could then simply call anchorCenterXToSuperview() on any UIView to centre any object.
Don't forget to make sure you've added your view to a view hierarchy before attempting to layout your views otherwise you'll get errors.