UITableViewFooter height issue - ios

Question

In my app I have an UITableView with a header created with .xib, this is the class:
class ViewHomeHeader: UIView {
class func instanceFromNib() -> ViewHomeHeader {
return UINib(nibName: "ViewHomeHeader", bundle: nil).instantiate(withOwner: self, options: nil).first as! ViewHomeHeader
}
}
I'm adding it to tableHeaderView:
let viewHomeHeader = ViewHomeHeader.instanceFromNib()
tableView.tableHeaderView = viewHomeHeader
This is the .xib with just one label and its relative constraints.
That's the result if I run on simulator (same on device)
I can't understand why the height is bigger than 21.
With the "Debug View Hierarchy" I can see that is not using the label height but the UIView-Encapsulated-Layout-Height
Console log:
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(
"<NSLayoutConstraint:0x28079f9d0 UILabel:0x104529b80'Label'.height == 21 (active)>",
"<NSLayoutConstraint:0x2807ac0a0 UILayoutGuide:0x281d9d500'UIViewSafeAreaLayoutGuide'.bottom == UILabel:0x104529b80'Label'.bottom + 17 (active)>",
"<NSLayoutConstraint:0x2807ac140 UILabel:0x104529b80'Label'.top == UILayoutGuide:0x281d9d500'UIViewSafeAreaLayoutGuide'.top + 18 (active)>",
"<NSLayoutConstraint:0x2807ae490 'UIView-Encapsulated-Layout-Height' Jordy.ViewHomeHeader:0x104529790.height == 143 (active)>",
"<NSLayoutConstraint:0x2807ac000 'UIViewSafeAreaLayoutGuide-bottom' V:[UILayoutGuide:0x281d9d500'UIViewSafeAreaLayoutGuide']-(0)-| (active, names: '|':Jordy.ViewHomeHeader:0x104529790 )>",
"<NSLayoutConstraint:0x28079fc50 'UIViewSafeAreaLayoutGuide-top' V:|-(0)-[UILayoutGuide:0x281d9d500'UIViewSafeAreaLayoutGuide'] (active, names: '|':Jordy.ViewHomeHeader:0x104529790 )>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x28079f9d0 UILabel:0x104529b80'Label'.height == 21 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.

Answer 1

As specified in the documentation:
When assigning a view to this property, set the height of that view to
a nonzero value. The table view respects only the height of your
view's frame rectangle; it adjusts the width of your header view
automatically to match the table view's width.
So you have to set the header size before setting it.
If your header has a height which depends on its content, here is a possible solution:
let header = HeaderView()
let widthConstraint = header.widthAnchor.constraint(equalToConstant: view.bounds.width)
header.translatesAutoresizingMaskIntoConstraints = false
widthConstraint.isActive = true
let targetSize = header.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
header.frame.size.height = targetSize.height
widthConstraint.isActive = false
header.translatesAutoresizingMaskIntoConstraints = true
tableView.tableHeaderView = header
Wait viewDidLayoutSubviews() to get the actual size of the view.
If your content is static, simply set its height:
let header = HeaderView()
header.frame.size.height = 30
tableView.tableHeaderView = header
Note that the header's autoresizingMask should not contain flexibleHeight (check your xib). The header should keep the height specified.

Answer 2

You can give lower priority to the bottom spacing constraint and higher priority to height constraint