TableHeaderView - variable height

extension UITableView {

  /// Variable-height UITableView tableHeaderView with autolayout
  ///
  /// Source: https://gist.github.com/marcoarment/1105553afba6b4900c10
	func layoutTableHeaderView() {

		guard let headerView = self.tableHeaderView else { return }
		headerView.translatesAutoresizingMaskIntoConstraints = false

		let headerWidth = headerView.bounds.size.width
		let temporaryWidthConstraints = NSLayoutConstraint.constraints(
			withVisualFormat: "[headerView(width)]",
			options: NSLayoutConstraint.FormatOptions(rawValue: UInt(0)),
			metrics: ["width": headerWidth], views: ["headerView": headerView])

		headerView.addConstraints(temporaryWidthConstraints)

		headerView.setNeedsLayout()
		headerView.layoutIfNeeded()

		let headerSize = headerView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
		let height = headerSize.height
		var frame = headerView.frame

		frame.size.height = height
		headerView.frame = frame

		self.tableHeaderView = headerView

		headerView.removeConstraints(temporaryWidthConstraints)
		headerView.translatesAutoresizingMaskIntoConstraints = true
	}
}