ios swift5 let tableHeaderView automatically row height tableHeaderView adaptive height according to content

• There is no parent view before headView, and there is no need to set frame
• Make the layout of the subview in the headView can give him a certain height
• Then call the following code and it's ok (my own test is valid)

 let size = headView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
 let rect = CGRect(x: 0, y: 0, width: 0, height: size.height)
 headView.frame = rect
 tableView.tableHeaderView = contentView

Reference blog:
tableHeaderView adaptive height - short book