Repo created

iphone/Maps/UI/Search/SearchOnMap/PlaceholderView.swift

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+final class PlaceholderView: UIView {
+
+  private let activityIndicator: UIActivityIndicatorView?
+  private let titleLabel = UILabel()
+  private let subtitleLabel = UILabel()
+  private let stackView = UIStackView()
+  private var keyboardHeight: CGFloat = 0
+  private var centerYConstraint: NSLayoutConstraint!
+  private var containerModalYTranslation: CGFloat = 0
+  private let minOffsetFromTheKeyboardTop: CGFloat = 20
+  private let maxOffsetFromTheTop: CGFloat = 100
+
+  init(title: String? = nil, subtitle: String? = nil, hasActivityIndicator: Bool = false) {
+    self.activityIndicator = hasActivityIndicator ? UIActivityIndicatorView() : nil
+    super.init(frame: .zero)
+    setupView(title: title, subtitle: subtitle)
+    layoutView()
+    setupKeyboardObservers()
+  }
+
+  @available(*, unavailable)
+  required init?(coder: NSCoder) {
+    fatalError("init(coder:) has not been implemented")
+  }
+
+  deinit {
+    NotificationCenter.default.removeObserver(self)
+  }
+
+  private func setupKeyboardObservers() {
+    NotificationCenter.default.addObserver(self,
+                                           selector: #selector(keyboardWillShow(_:)),
+                                           name: UIResponder.keyboardWillShowNotification,
+                                           object: nil)
+    NotificationCenter.default.addObserver(self,
+                                           selector: #selector(keyboardWillHide(_:)),
+                                           name: UIResponder.keyboardWillHideNotification,
+                                           object: nil)
+  }
+
+  @objc private func keyboardWillShow(_ notification: Notification) {
+    if let keyboardFrame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect {
+      keyboardHeight = keyboardFrame.height
+      reloadConstraints()
+    }
+  }
+
+  @objc private func keyboardWillHide(_ notification: Notification) {
+    keyboardHeight = 0
+    reloadConstraints()
+  }
+
+  override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
+    super.traitCollectionDidChange(previousTraitCollection)
+    if traitCollection.verticalSizeClass != previousTraitCollection?.verticalSizeClass {
+      reloadConstraints()
+    }
+  }
+
+  private func setupView(title: String?, subtitle: String?) {
+    if let activityIndicator = activityIndicator {
+      activityIndicator.hidesWhenStopped = true
+      activityIndicator.startAnimating()
+      activityIndicator.style = .medium
+    }
+
+    titleLabel.text = title
+    titleLabel.setFontStyle(.medium16, color: .blackPrimary)
+    titleLabel.textAlignment = .center
+    titleLabel.numberOfLines = 0
+
+    subtitleLabel.text = subtitle
+    subtitleLabel.setFontStyle(.regular14, color: .blackSecondary)
+    subtitleLabel.textAlignment = .center
+    subtitleLabel.isHidden = subtitle == nil
+    subtitleLabel.numberOfLines = 0
+
+    stackView.axis = .vertical
+    stackView.alignment = .fill
+    stackView.spacing = 8
+  }
+
+  private func layoutView() {
+    if let activityIndicator = activityIndicator {
+      stackView.addArrangedSubview(activityIndicator)
+    }
+    if let title = titleLabel.text, !title.isEmpty {
+      stackView.addArrangedSubview(titleLabel)
+    }
+    if let subtitle = subtitleLabel.text, !subtitle.isEmpty {
+      stackView.addArrangedSubview(subtitleLabel)
+    }
+
+    addSubview(stackView)
+    stackView.translatesAutoresizingMaskIntoConstraints = false
+
+    centerYConstraint = stackView.centerYAnchor.constraint(equalTo: centerYAnchor)
+    NSLayoutConstraint.activate([
+      stackView.centerXAnchor.constraint(equalTo: centerXAnchor),
+      stackView.widthAnchor.constraint(lessThanOrEqualTo: widthAnchor, multiplier: 0.8),
+      centerYConstraint
+    ])
+  }
+
+  private func reloadConstraints() {
+    let offset = keyboardHeight > 0 ? max(bounds.height / 2 - keyboardHeight, minOffsetFromTheKeyboardTop + stackView.frame.height) : containerModalYTranslation / 2
+    let maxOffset = bounds.height / 2 - maxOffsetFromTheTop
+    centerYConstraint.constant = -min(offset, maxOffset)
+    UIView.animate(withDuration: kDefaultAnimationDuration, delay: .zero, options: [.beginFromCurrentState, .curveEaseOut]) {
+      self.layoutIfNeeded()
+    }
+  }
+}
+
+// MARK: - ModallyPresentedViewController
+extension PlaceholderView: ModallyPresentedViewController {
+  func presentationFrameDidChange(_ frame: CGRect) {
+    self.containerModalYTranslation = frame.origin.y
+    reloadConstraints()
+  }
+}