I'd like to display a list of Keychain items using Touch ID when focusing on a text field, as shown in the image below. I've looked through the documentation but couldn't find an API that can produce the desired effect as shown in the image. It seems to me that there isn't an API for this and I would need to implement it manually. However, I'm wondering if there might be an API that I'm not aware of. References: https://developer.apple.com/documentation/localauthentication , https://developer.apple.com/documentation/localauthenticationembeddedui/laauthenticationview

Hi, I'm trouble in making good motion between UILabel and UIButton when UIButton changes its height. If you click UIButton to result in longer its height, UILabel(red) will be short. Okay That's good. But my question is that when UILabel(red) is going to be short why it's bottom anchor is moving shortly up and down ? I just changed button height constraint when button is clicked. UILabel (red) bottom constraint is still self.view.bottom.anchor. I questioned this problem to other developer, I get other solution using UIView instead of UILabel. But they didn't know why UILabel was going to be somethings like error. They thought that was maybe because of UILabel's intrinsicContentSize . But I still clearly don't know why was happened. I would appreciate you if you give me clear answer. thanks! here is my entire code. you can run exactly just copy and paste. import UIKit class ViewController3 : UIViewController {       var greenLabel = UILabel()   var redLabel = UILabel()   var button = UIButton(type : .custom)       var buttonConstraints : NSLayoutConstraint?   var isClicked = false       override func viewDidLoad() {     super.viewDidLoad()                 self.view.backgroundColor = .white     self.view.addSubview(greenLabel)     self.view.addSubview(redLabel )     self.view.addSubview(button)         button.backgroundColor = .blue     redLabel.backgroundColor = .red     greenLabel.backgroundColor = .green          button.setTitle("I'm Button", for: .normal)     button.addTarget(self, action: #selector(click), for: .touchUpInside)           redLabel.translatesAutoresizingMaskIntoConstraints = false     greenLabel.translatesAutoresizingMaskIntoConstraints = false     button.translatesAutoresizingMaskIntoConstraints = false                 buttonConstraints = button.heightAnchor.constraint(equalToConstant: 50)            NSLayoutConstraint.activate([       buttonConstraints!,       greenLabel.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100),       greenLabel.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: 10),       greenLabel.trailingAnchor.constraint(equalTo: self.view.trailingAnchor, constant: -10),       greenLabel.heightAnchor.constraint(equalToConstant: 50),               button.topAnchor.constraint(equalTo: self.greenLabel.bottomAnchor, constant: 50),       button.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: 10),       button.trailingAnchor.constraint(equalTo: self.view.trailingAnchor, constant: -10),               redLabel.topAnchor.constraint(equalTo: self.button.bottomAnchor, constant: 50),       redLabel.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: 10),       redLabel.trailingAnchor.constraint(equalTo: self.view.trailingAnchor, constant: -10),       redLabel.bottomAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor),     ])   }   @objc func click() {           switch isClicked {     case true :               UIView.animate(withDuration: 0.5, delay: 0.0, animations: {         self.buttonConstraints?.constant = 50         self.view.layoutIfNeeded()                 }, completion: { complete in         self.isClicked = false                 })             case false :               UIView.animate(withDuration: 0.5, delay: 0.0, animations: {         self.buttonConstraints?.constant = 200         self.view.layoutIfNeeded()       }, completion : { complete in         self.isClicked = true       })             }   } }