Replace Slint UI with UIKit and add milestones

Fixes #2.\nFixes #9.

ios/Sources/Support.swift

@@ -0,0 +1,140 @@
+import UIKit
+
+func errorAlert(_ message: String) -> UIAlertController {
+    let alert = UIAlertController(title: "Something went wrong", message: message, preferredStyle: .alert)
+    alert.addAction(UIAlertAction(title: "OK", style: .default))
+    return alert
+}
+
+extension UIViewController {
+    func show(error: Error) {
+        present(errorAlert(error.localizedDescription), animated: true)
+    }
+
+    func beginNavigationLoading(_ spinner: UIActivityIndicatorView) {
+        guard navigationItem.rightBarButtonItem == nil else { return }
+        spinner.startAnimating()
+        navigationItem.rightBarButtonItem = UIBarButtonItem(customView: spinner)
+    }
+
+    func endNavigationLoading(_ spinner: UIActivityIndicatorView) {
+        spinner.stopAnimating()
+        if navigationItem.rightBarButtonItem?.customView === spinner {
+            navigationItem.rightBarButtonItem = nil
+        }
+    }
+}
+
+@MainActor
+class RefreshingTableViewController: UITableViewController {
+    private let spinner = UIActivityIndicatorView(style: .medium)
+    var loadingTask: Task<Void, Never>?
+
+    init() {
+        super.init(style: .plain)
+        tableView.backgroundColor = .systemGroupedBackground
+        tableView.separatorInset = .zero
+        tableView.refreshControl = UIRefreshControl()
+        tableView.refreshControl?.addTarget(self, action: #selector(refreshRequested), for: .valueChanged)
+        navigationItem.largeTitleDisplayMode = .never
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) { fatalError("init(coder:) is not supported") }
+
+    deinit { loadingTask?.cancel() }
+
+    func loadContent(refreshing: Bool) {}
+
+    func beginLoading(refreshing: Bool) {
+        if !refreshing { beginNavigationLoading(spinner) }
+    }
+
+    func endLoading() {
+        endNavigationLoading(spinner)
+        refreshControl?.endRefreshing()
+    }
+
+    @objc private func refreshRequested() {
+        loadContent(refreshing: true)
+    }
+}
+
+final class EmptyBackgroundView: UIView {
+    init(title: String, detail: String) {
+        super.init(frame: .zero)
+        let titleLabel = UILabel()
+        titleLabel.text = title
+        titleLabel.font = .preferredFont(forTextStyle: .title2)
+        titleLabel.textAlignment = .center
+        let detailLabel = UILabel()
+        detailLabel.text = detail
+        detailLabel.font = .preferredFont(forTextStyle: .body)
+        detailLabel.textColor = .secondaryLabel
+        detailLabel.textAlignment = .center
+        detailLabel.numberOfLines = 0
+        let stack = UIStackView(arrangedSubviews: [titleLabel, detailLabel])
+        stack.axis = .vertical
+        stack.spacing = 8
+        stack.translatesAutoresizingMaskIntoConstraints = false
+        addSubview(stack)
+        NSLayoutConstraint.activate([
+            stack.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 28),
+            stack.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -28),
+            stack.centerYAnchor.constraint(equalTo: centerYAnchor, constant: -40),
+        ])
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) { fatalError("init(coder:) is not supported") }
+}
+
+extension UIColor {
+    convenience init?(hex: String) {
+        let value = hex.trimmingCharacters(in: CharacterSet(charactersIn: "#"))
+        guard value.count == 6, let rgb = Int(value, radix: 16) else { return nil }
+        self.init(
+            red: CGFloat((rgb >> 16) & 0xff) / 255,
+            green: CGFloat((rgb >> 8) & 0xff) / 255,
+            blue: CGFloat(rgb & 0xff) / 255,
+            alpha: 1
+        )
+    }
+}
+
+func markdown(_ source: String, textStyle: UIFont.TextStyle = .body) -> NSAttributedString {
+    let attributed = (try? AttributedString(
+        markdown: source,
+        options: .init(interpretedSyntax: .full)
+    )) ?? AttributedString(source)
+    var mutable = attributed
+    mutable.font = .preferredFont(forTextStyle: textStyle)
+    mutable.foregroundColor = UIColor.label
+    return NSAttributedString(mutable)
+}
+
+func configureTextCell(_ cell: UITableViewCell, title: String, detail: String, image: UIImage? = nil) {
+    var content = cell.defaultContentConfiguration()
+    content.text = title
+    content.secondaryText = detail
+    content.secondaryTextProperties.numberOfLines = 2
+    content.image = image
+    content.imageProperties.tintColor = .tintColor
+    cell.contentConfiguration = content
+    cell.backgroundColor = .systemBackground
+}
+
+func symbolText(_ symbol: String, text: String, font: UIFont, color: UIColor) -> NSAttributedString {
+    let output = NSMutableAttributedString()
+    if let image = UIImage(systemName: symbol)?.withTintColor(color, renderingMode: .alwaysOriginal) {
+        let attachment = NSTextAttachment(image: image)
+        attachment.bounds = CGRect(x: 0, y: -2, width: font.pointSize, height: font.pointSize)
+        output.append(NSAttributedString(attachment: attachment))
+        output.append(NSAttributedString(string: "  "))
+    }
+    output.append(NSAttributedString(string: text, attributes: [
+        .font: font,
+        .foregroundColor: color,
+    ]))
+    return output
+}