Swift: Getting 'Snapshotting a view that has not been rendered..' error when trying to open a URL in safari from my app

Question

One of the specifications of my app is that on tapping a tableView cell, the user will be redirected to the website associated with the cell. Here is the code:

Answer 1

I was facing the similar problem (same warning XD).

Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.

My Xcode version is 9.4.1, and everything was perfect until I add resignFirstResponder() in textFieldShouldReturn(_ textField: UITextField).

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Here was my situation:

When I touched UITextField with text in the UITableViewCell, It will show the warning.

So I changed the way to trigger UITextField(Edit version). It never show the warning again.

In conclusion, I still don't know why this happened, but what I can do is avoid the warning, hope It will help someone :D

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Edited code:

class TableViewCell: UITableViewCell {
    // add this in TableViewCell
    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)
        answerTextField.isEnabled = selected
        if selected {
            answerTextField.becomeFirstResponder()
        } else {
            answerTextField.resignFirstResponder()
        }
    }
}

Original code:

class ViewController: UIViewController {

    private let tableView: UITableView = {
        let t = UITableView()
        t.separatorStyle = .none
        t.backgroundColor = .clear
        return t
    }()

    private let cellId = "Cell"

    private let data = [
        Model(title: "A", answer: "a"),
        Model(title: "B", answer: "b"),
        Model(title: "C", answer: nil),
        Model(title: "D", answer: nil)
    ]

    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.dataSource = self
        tableView.delegate = self
        tableView.register(TableViewCell.self, forCellReuseIdentifier: cellId)
        view.addSubview(tableView)
        tableView.frame = view.frame
    }
}

extension ViewController: UITableViewDataSource, UITableViewDelegate {

    func numberOfSections(in tableView: UITableView) -> Int {
        return 3
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return data.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        if let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as? TableViewCell {
            cell.contentView.backgroundColor = indexPath.section % 2 == 0 ? .gray : .white
            cell.setData(data[indexPath.row])
            return cell
        }
        return UITableViewCell()
    }

    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 100
    }
}

class TableViewCell: UITableViewCell {

    private let titleLabel = UILabel()
    private let answerTextField = UITextField()

    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        setupViews()
    }
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupViews()
    }

    func setupViews() {
        setupTitleLabels()
    }

    func setData(_ data: Model) {
        titleLabel.text = data.title
        answerTextField.text = data.answer
    }

    private func setupTitleLabels() {
        answerTextField.delegate = self

        let sv = UIStackView(arrangedSubviews: [titleLabel, answerTextField])
        sv.axis = .vertical
        sv.spacing = 0
        sv.distribution = .fill

        contentView.addSubview(sv)
        sv.topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
        sv.leftAnchor.constraint(equalTo: contentView.leftAnchor).isActive = true
        sv.bottomAnchor.constraint(equalTo: contentView.bottomAnchor).isActive = true
        sv.rightAnchor.constraint(equalTo: contentView.rightAnchor).isActive = true
    }
}

extension TableViewCell: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }
}

struct Model {
    let title: String
    var answer: String?
    init(title: String, answer: String? = nil) {
        self.title = title
        self.answer = answer
    }
}