Self sized UITableView

SelfSizedTableView.swift

import UIKit

class SelfSizedTableView: UITableView {
    lazy var heightConstraint: NSLayoutConstraint = {
        let constraint = NSLayoutConstraint(item: self, attribute: .height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: bounds.height)
        return constraint
    }()

    override init(frame: CGRect, style: UITableViewStyle) {
        super.init(frame: frame, style: style)
        setup()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }

    private func setup() {
        heightConstraint.isActive = true
        addObserver(self, forKeyPath: "contentSize", options: .new, context: nil)
    }

    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey: Any]?, context: UnsafeMutableRawPointer?) {
        if let obj = object as? UITableView, obj == self && keyPath == "contentSize" {
            heightConstraint.constant = contentSize.height
            superview?.layoutIfNeeded()
        }
    }
}