Unable to activate constraint with anchors.... because they have no common ancestor

I am attempting to create a Swift-based UI programmatically that resembles the layout shown below

Below is my view hierarchy which I created using xib. Now I'm attempting to achieve the same through programatically.

Below is the code which i'm attempting. Here JTACDayCell is the child of UICollectionViewCell

FYI: JTACDayCell belongs to JTAppleCalendar library

class DateTableCell: JTACDayCell {
static let reuseID = "dateCell"
lazy var parentView: UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    return view
}()

lazy var selectedView: UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    return view
}()

lazy var dateLabel: UILabel = {
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    return label
}()

lazy var eventView: UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    return view
}()

lazy var separatorView: UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    view.backgroundColor = .lightGray
    return view
}()

override init(frame: CGRect) {
    super.init(frame: frame)
    setUpAutoLayout()
    
    parentView.addSubview(selectedView)
    parentView.addSubview(dateLabel)
    parentView.addSubview(eventView)
    
    addSubview(parentView)
    addSubview(separatorView)
}

required init?(coder: NSCoder) {
    fatalError("init?(coder: NSCoder) has not been implemented")
}

private func setUpAutoLayout() {
    NSLayoutConstraint.activate([
        parentView.leftAnchor.constraint(equalTo: leftAnchor),
        parentView.rightAnchor.constraint(equalTo: rightAnchor),
        parentView.topAnchor.constraint(equalTo: topAnchor),
        parentView.bottomAnchor.constraint(equalTo: separatorView.topAnchor),
        
        selectedView.centerXAnchor.constraint(equalTo: parentView.centerXAnchor),
        selectedView.centerYAnchor.constraint(equalTo: parentView.centerYAnchor, constant: -2.5),
        selectedView.widthAnchor.constraint(equalToConstant: 35),
        selectedView.heightAnchor.constraint(equalToConstant: 35),
        
        dateLabel.centerXAnchor.constraint(equalTo: parentView.centerXAnchor),
        dateLabel.centerYAnchor.constraint(equalTo: parentView.centerYAnchor, constant: -2.5),
        
        eventView.centerXAnchor.constraint(equalTo: parentView.centerXAnchor),
        eventView.widthAnchor.constraint(equalToConstant: 6),
        eventView.heightAnchor.constraint(equalToConstant: 6),
        eventView.bottomAnchor.constraint(equalTo: parentView.topAnchor, constant: 5),
        
        separatorView.leftAnchor.constraint(equalTo: leftAnchor),
        separatorView.rightAnchor.constraint(equalTo: rightAnchor),
        separatorView.heightAnchor.constraint(equalToConstant: 0.5),
        separatorView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: 1)
    ])
}
}

Upon executing the provided code, I encounter the following error

*** Terminating app due to uncaught exception 'NSGenericException', reason: 'Unable to activate constraint with anchors <NSLayoutXAxisAnchor:0x6000034619c0 "UIView:0x7fb1a8a20ce0.left"> and <NSLayoutXAxisAnchor:0x600003460800 "AppName.DateTableCell:0x7fb1a8a28470.left"> because they have no common ancestor. Does the constraint or its anchors reference items in different view hierarchies? That's illegal.'

What might be the issue here?

Call your setUpAutoLayout() function after added subviews

override init(frame: CGRect) {
    super.init(frame: frame)
    
    
    parentView.addSubview(selectedView)
    parentView.addSubview(dateLabel)
    parentView.addSubview(eventView)
    
    addSubview(parentView)
    addSubview(separatorView)

    setUpAutoLayout()
}