add UKAvatar implementation

Author: mikhailChelbaev

Examples/DemosApp/DemosApp/ComponentsPreview/PreviewPages/AvatarPreview.swift

@@ -9,6 +9,10 @@ struct AvatarPreview: View {
 
   var body: some View {
     VStack {
+      PreviewWrapper(title: "UIKit") {
+        UKAvatar(model: self.model)
+          .preview
+      }
       PreviewWrapper(title: "SwiftUI") {
         SUAvatar(model: self.model)
       }

Sources/ComponentsKit/Components/Avatar/Models/AvatarVM.swift

@@ -129,3 +129,13 @@ extension AvatarVM {
     }
   }
 }
+
+// MARK: - UIKit Helpers
+
+extension AvatarVM {
+  func shouldUpdateImage(_ oldModel: Self) -> Bool {
+    return self.imageSrc != oldModel.imageSrc
+    || self.placeholder != oldModel.placeholder
+    || self.color != oldModel.color
+  }
+}

Sources/ComponentsKit/Components/Avatar/UKAvatar.swift

@@ -0,0 +1,119 @@
+import UIKit
+
+/// A UIKit component that displays a profile picture, initials or fallback icon for a user.
+open class UKAvatar: UIImageView, UKComponent {
+  // MARK: - Properties
+
+  /// A model that defines the appearance properties.
+  public var model: AvatarVM {
+    didSet {
+      self.update(oldValue)
+    }
+  }
+
+  private var loadedImage: (url: URL, image: UIImage)?
+
+  // MARK: - UIView Properties
+
+  open override var intrinsicContentSize: CGSize {
+    return self.sizeThatFits(UIView.layoutFittingExpandedSize)
+  }
+
+  // MARK: - Initializers
+
+  /// Initializer.
+  /// - Parameters:
+  ///   - model: A model that defines the appearance properties.
+  public init(model: AvatarVM = .init()) {
+    self.model = model
+
+    super.init(frame: .zero)
+
+    self.style()
+  }
+
+  public required init?(coder: NSCoder) {
+    fatalError("init(coder:) has not been implemented")
+  }
+
+  // MARK: - Style
+
+  private func style() {
+    self.contentMode = .scaleToFill
+    self.clipsToBounds = true
+  }
+
+  // MARK: - Update
+
+  public func update(_ oldModel: AvatarVM) {
+    guard self.model != oldModel else { return }
+
+    if self.model.shouldUpdateImage(oldModel) {
+      self.updateImage()
+    }
+    if self.model.cornerRadius != oldModel.cornerRadius {
+      self.layer.cornerRadius = self.model.cornerRadius.value(for: self.bounds.height)
+    }
+    if self.model.size != oldModel.size {
+      self.setNeedsLayout()
+      self.invalidateIntrinsicContentSize()
+    }
+  }
+
+  // MARK: - Layout
+
+  open override func layoutSubviews() {
+    super.layoutSubviews()
+
+    self.layer.cornerRadius = self.model.cornerRadius.value(for: self.bounds.height)
+
+    self.updateImage()
+  }
+
+  // MARK: - UIView Methods
+
+  open override func sizeThatFits(_ size: CGSize) -> CGSize {
+    let minProvidedSide = min(size.width, size.height)
+    let minPreferredSide = min(self.model.preferredSize.width, self.model.preferredSize.height)
+    let side = min(minProvidedSide, minPreferredSide)
+    return CGSize(width: side, height: side)
+  }
+
+  // MARK: - Helpers
+
+  private func downloadImage(url: URL) {
+    self.loadedImage = nil
+    Task { @MainActor in
+      guard let image = await ImageLoader.download(url: url),
+            url == self.model.imageURL
+      else { return }
+
+      self.loadedImage = (url, image)
+      UIView.transition(
+        with: self,
+        duration: 0.2,
+        options: .transitionCrossDissolve,
+        animations: {
+          self.image = image
+        }
+      )
+    }
+  }
+
+  private func updateImage() {
+    let size = self.bounds.size
+    switch self.model.imageSrc {
+    case .remote(let url):
+      if let loadedImage, loadedImage.url == url {
+        self.image = loadedImage.image
+      } else {
+        self.image = self.model.placeholderImage(for: size)
+        self.downloadImage(url: url)
+      }
+    case let .local(name, bundle):
+      self.image = UIImage(named: name, in: bundle, compatibleWith: nil) ?? self.model.placeholderImage(for: size)
+    case .none:
+      self.image = self.model.placeholderImage(for: size)
+    }
+  }
+}

Sources/ComponentsKit/Components/Divider/UKDivider.swift

@@ -32,7 +32,7 @@ open class UKDivider: UIView, UKComponent {
     fatalError("init(coder:) has not been implemented")
   }
 
-  // MARK: - Setup
+  // MARK: - Style
 
   private func style() {
     self.backgroundColor = self.model.lineColor.uiColor