Xcode Constraint Break When Switching Between Text Fields Without Dismissing Keyboard

I believe that this is a bug in apple's implementation of the keyboard.

So the work around for this is set autocorrection type of text field to no

textField.autocorrectionType = .no

You might be facing issue, while setting constraints, so I've done it, similar to you, and able to tap on the next textfield without dismissing the keyboard first.

I've tested below solution. You can try this solution.

I hope it will solve your issue.

class ViewController: UIViewController {

    let nameTextField: UITextField = {
        let textField = UITextField()
        textField.placeholder = "Enter your name here"
        textField.layer.borderWidth = 1
        textField.borderStyle = .roundedRect
        textField.translatesAutoresizingMaskIntoConstraints = false
        return textField
    }()

    let ageTextField: UITextField = {
        let textField = UITextField()
        textField.placeholder = "Enter your age here"
        textField.keyboardType = .decimalPad
        textField.layer.borderWidth = 1
        textField.borderStyle = .roundedRect
        textField.translatesAutoresizingMaskIntoConstraints = false
        return textField
    }()

    let cityTextField: UITextField = {
        let textField = UITextField()
        textField.placeholder = "Enter your city name here"
        textField.layer.borderWidth = 1
        textField.borderStyle = .roundedRect
        textField.translatesAutoresizingMaskIntoConstraints = false
        return textField
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.view.addSubview(nameTextField)
        self.view.addSubview(ageTextField)
        self.view.addSubview(cityTextField)

        NSLayoutConstraint.activate([

            //nameTextField
            self.nameTextField.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor, constant: 100),
            self.nameTextField.leadingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.leadingAnchor, constant: 16),
            self.nameTextField.trailingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.trailingAnchor, constant: -16),


            //ageTextField
            self.ageTextField.topAnchor.constraint(equalTo: self.nameTextField.bottomAnchor, constant: 16),
            self.ageTextField.leadingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.leadingAnchor, constant: 16),
            self.ageTextField.trailingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.trailingAnchor, constant: -16),

            //cityTextField
            self.cityTextField.topAnchor.constraint(equalTo: self.ageTextField.bottomAnchor, constant: 16),
            self.cityTextField.leadingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.leadingAnchor, constant: 16),
            self.cityTextField.trailingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.trailingAnchor, constant: -16),

            ])
    }
}