Show error in UITextField SWIFT XCODE

I have the following extension

private var rightViews = NSMapTable<UITextField, UIView>(keyOptions: NSPointerFunctions.Options.weakMemory, valueOptions: NSPointerFunctions.Options.strongMemory)
private var errorViews = NSMapTable<UITextField, UIView>(keyOptions: NSPointerFunctions.Options.weakMemory, valueOptions: NSPointerFunctions.Options.strongMemory)

        extension UITextField {
        // Add/remove error message
        func setError(_ string: String? = nil, show: Bool = true) {
            if let rightView = rightView, rightView.tag != 999 {
                rightViews.setObject(rightView, forKey: self)
            }



            // Remove message
            guard string != nil else {
                if let rightView = rightViews.object(forKey: self) {
                    self.rightView = rightView
                    rightViews.removeObject(forKey: self)
                } else {
                    self.rightView = nil
                }

                if let errorView = errorViews.object(forKey: self) {
                    errorView.isHidden = true
                    errorViews.removeObject(forKey: self)
                }

                return
            }

            // Create container
            let container = UIView()
            container.translatesAutoresizingMaskIntoConstraints = false

            // Create triangle
            let triagle = TriangleTop()
            triagle.backgroundColor = .clear
            triagle.translatesAutoresizingMaskIntoConstraints = false
            container.addSubview(triagle)

            // Create red line
            let line = UIView()
            line.backgroundColor = .red
            line.translatesAutoresizingMaskIntoConstraints = false
            container.addSubview(line)

            // Create message
            let label = UILabel()
            label.text = string
            label.textColor = .white
            label.numberOfLines = 0
            label.font = UIFont.systemFont(ofSize: 15)
            label.backgroundColor = .black
            label.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 250), for: .horizontal)
            label.translatesAutoresizingMaskIntoConstraints = false
            container.addSubview(label)

            // Set constraints for triangle
            triagle.heightAnchor.constraint(equalToConstant: 10).isActive = true
            triagle.widthAnchor.constraint(equalToConstant: 15).isActive = true
            triagle.topAnchor.constraint(equalTo: container.topAnchor, constant: -10).isActive = true
            triagle.trailingAnchor.constraint(equalTo: container.trailingAnchor, constant: -15).isActive = true

            // Set constraints for line
            line.heightAnchor.constraint(equalToConstant: 3).isActive = true
            line.topAnchor.constraint(equalTo: triagle.bottomAnchor, constant: 0).isActive = true
            line.leadingAnchor.constraint(equalTo: container.leadingAnchor, constant: 0).isActive = true
            line.trailingAnchor.constraint(equalTo: container.trailingAnchor, constant: 0).isActive = true

            // Set constraints for label
            label.topAnchor.constraint(equalTo: line.bottomAnchor, constant: 0).isActive = true
            label.bottomAnchor.constraint(equalTo: container.bottomAnchor, constant: 0).isActive = true
            label.leadingAnchor.constraint(equalTo: container.leadingAnchor, constant: 0).isActive = true
            label.trailingAnchor.constraint(equalTo: container.trailingAnchor, constant: 0).isActive = true

            if !show {
                container.isHidden = true
            }
            // superview!.superview!.addSubview(container)
    //        UIApplication.shared.keyWindow!.addSubview(container)

            self.addSubview(container)

            // Set constraints for container
            container.widthAnchor.constraint(lessThanOrEqualTo: superview!.widthAnchor, multiplier: 1).isActive = true
            container.trailingAnchor.constraint(equalTo: superview!.trailingAnchor, constant: 0).isActive = true
            container.topAnchor.constraint(equalTo: superview!.bottomAnchor, constant: 0).isActive = true

            // Hide other error messages
            let enumerator = errorViews.objectEnumerator()
            while let view = enumerator!.nextObject() as! UIView? {
                view.isHidden = true
            }

            // Add right button to textField
            let errorButton = UIButton(type: .custom)
            errorButton.tag = 999
            errorButton.setImage(UIImage(named: "ic_error"), for: .normal)
            errorButton.frame = CGRect(x: 0, y: 0, width: frame.size.height, height: frame.size.height)
            errorButton.addTarget(self, action: #selector(errorAction), for: .touchUpInside)
            rightView = errorButton
            rightViewMode = .always

            // Save view with error message
            errorViews.setObject(container, forKey: self)
        }

which generates me

Which places it at the end of the view as you can see

what I want is to be able to leave each error below each box instead of putting it at the bottom of the view

I know this problem is here

 self.addSubview(container)

How could I modify this extension so that it is placed below each box instead of being placed below the view, thanks in advance