animation sample for SwiftLayout

final class PreviewView: UIView, LayoutBuilding {
    
    var capTop = true {
        didSet {
            UIView.animate(withDuration: 1.0) {
                self.updateLayout()
            }
        }
    }
    
    let cap = UIButton()
    let shoe = UIButton()
    let title = UILabel()
    
    var top: UIButton { capTop ? cap : shoe }
    var bottom: UIButton { capTop ? shoe : cap }
    
    var deactivable: Deactivable?
    
    var layout: some Layout {
        self {
            top.anchors {
                Anchors.cap()
            }
            bottom.anchors {
                Anchors(.top).equalTo(top.bottomAnchor)
                Anchors(.height).equalTo(top)
                Anchors.shoe()
            }
            title.config { label in
                label.text = "Top Title"
                UIView.transition(with: label, duration: 1.0, options: [.beginFromCurrentState, .transitionCrossDissolve], animations: {
                    label.textColor = self.capTop ? .black : .yellow
                }, completion: nil)
            }.anchors {
                Anchors(.centerX, .centerY).equalTo(top)
            }
            UILabel().config { label in
                label.text = "Bottom Title"
                label.textColor = capTop ? .yellow : .black
            }.identifying("title.bottom").anchors {
                Anchors(.centerX, .centerY).equalTo(bottom)
            }
        }
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        initViews()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        initViews()
    }
    
    func initViews() {
        cap.backgroundColor = .yellow
        shoe.backgroundColor = .black
        cap.addAction(.init(handler: { [weak self] _ in
            self?.capTop.toggle()
        }), for: .touchUpInside)
        shoe.addAction(.init(handler: { [weak self] _ in
            self?.capTop.toggle()
        }), for: .touchUpInside)
        self.accessibilityIdentifier = "root"
        updateIdentifiers(rootObject: self)
        updateLayout()
    }
    
}