CODEWITHSUNDEEP
swiftuitableviewautolayout
Namely
Namely

Reputation: 83

Getting constraint error while collapsing Tableview section

I have a custom cell view which contains an image and a label embedded in vertical Stack View.

Stack View is bound to 4 edges of Content View.

Image has constraint of 1:1 aspect.

Expand and collapse operations seem working fine however while I keep tapping, I see some warnings at some point and it seems random.

cell preview expanded row

2019-01-17 23:15:46.749683+0300 MyApp[10270:349316] [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:0x6000032e54a0 UIStackView:0x7f9f97d19620.height == 43.5   (active)>",
    "<NSLayoutConstraint:0x6000032e5590 V:[UIStackView:0x7f9f97d19620]-(5)-|   (active, names: '|':UITableViewCellContentView:0x7f9f97d19430 )>",
    "<NSLayoutConstraint:0x6000032e5630 V:|-(5)-[UIStackView:0x7f9f97d19620]   (active, names: '|':UITableViewCellContentView:0x7f9f97d19430 )>",
    "<NSLayoutConstraint:0x6000032e5f40 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x7f9f97d19430.height == 499.5   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x6000032e54a0 UIStackView:0x7f9f97d19620.height == 43.5   (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.

What I run to expand/collapse is follows:

....
tableView.register(UINib(nibName: "InboxTableViewCell", bundle: nil), forCellReuseIdentifier: "inboxCell")
        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 500
        tableView.reloadData()
....

func numberOfSections(in tableView: UITableView) -> Int {
        return tableViewData.count
    }


    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        if tableViewData[section].opened == true {
            return tableViewData[section].sectionData.count + 1
        }else  {
            return 1
        }
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        if indexPath.row == 0 {

            let cell = tableView.dequeueReusableCell(withIdentifier: "headerCell", for: indexPath) as! HeaderTableViewCell
            return cell
        } else {
            let cell = tableView.dequeueReusableCell(withIdentifier: "inboxCell", for: indexPath) as! InboxTableViewCell

            return cell
        }
    }

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        if indexPath.row == 0{
            if tableViewData[indexPath.section].opened == true {
                tableViewData[indexPath.section].opened = false
                let sections = IndexSet.init(integer: indexPath.section)
                tableView.reloadSections(sections, with: .none)

            }else{
                tableViewData[indexPath.section].opened = true
                let sections = IndexSet.init(integer: indexPath.section)
                tableView.reloadSections(sections, with: .none)

            }
        }
    }

Upvotes: 1

Views: 335

Answers (1)

cookednick
cookednick

Reputation: 1088

Set the image's 1:1 aspect ratio constraint's priority to 999 or lower. It's forcing Auto Layout to generate a height constraint for the stack view in order to uphold the aspect ratio. That's bad for business.

Upvotes: 2

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