Unable to simultaneously satisfy constraints Custom Header Section - ios

Question

I have a .nib for my custom header section for a table view:
override func viewDidLoad() {
super.viewDidLoad()
let nib = UINib(nibName: "BillTableSection", bundle: nil)
billTableView.register(nib, forHeaderFooterViewReuseIdentifier: "BillTableSection")
}
func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 44.0
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let cell = billTableView.dequeueReusableHeaderFooterView(withIdentifier: "BillTableSection")
return cell
}
The custom header section works, but whenever I insert a new section, A warning shows up on my console:
2017-10-02 14:56:32.791529+0800 Project[1017:14993] [LayoutConstraints] Unable to simultaneously satisfy constraints.
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:0x61000009f8b0 UIButton:0x7ff359d0d4a0.width == 22 (active)>",
"<NSLayoutConstraint:0x61000009f900 UITextField:0x7ff359d19660.width == UILabel:0x7ff359d17650'$0.00'.width (active)>",
"<NSLayoutConstraint:0x61000009fa90 UITextField:0x7ff359d19660.leading == UIView:0x7ff359d010a0.leadingMargin (active)>",
"<NSLayoutConstraint:0x61000009ed20 H:[UITextField:0x7ff359d19660]-(30)-[UILabel:0x7ff359d17650'$0.00'] (active)>",
"<NSLayoutConstraint:0x61000009f2c0 UIButton:0x7ff359d0d4a0.trailing == UIView:0x7ff359d010a0.trailingMargin (active)>",
"<NSLayoutConstraint:0x61000009ee60 H:[UILabel:0x7ff359d17650'$0.00']-(7)-[UIButton:0x7ff359d0d4a0] (active)>",
"<NSLayoutConstraint:0x61000009f5e0 H:[UIView:0x7ff359d010a0]-(0)-| (active, names: '|':Project.BillTableSection:0x7ff359d0fc70 )>",
"<NSLayoutConstraint:0x61000009f9a0 H:|-(0)-[UIView:0x7ff359d010a0] (active, names: '|':Project.BillTableSection:0x7ff359d0fc70 )>",
"<NSLayoutConstraint:0x61000009ff40 '_UITemporaryLayoutWidth' Project.BillTableSection:0x7ff359d0fc70.width == 0 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x61000009f8b0 UIButton:0x7ff359d0d4a0.width == 22 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
I tried to find the constraints that are not needed and remove them, but the layout I defined will not work on other devices anymore. Is it safe to ignore this warning? I'm not sure how to debug this... Please help!

Answer 1

You should lower the BtnAdd.trailing priority to less than 1000. it looks like autolayout adds a temporary constraint
"<NSLayoutConstraint:0x61000009ff40 '_UITemporaryLayoutWidth' Project.BillTableSection:0x7ff359d0fc70.width == 0 (active)>"
that squishes all the content, so removing that absolute priority will let your content adjust without conflicts.
Also, why is TxtName.width == LblPrice.width? Can't you adjust content hugging priority?