Extract shared cell dimming logic into DiffableTableViewCell base class

DiffableSubtitleTableViewCell and DiffableButtonTableViewCell now inherit
from DiffableTableViewCell instead of UITableViewCell directly, removing
duplicated image dimming, prepareForReuse and tintColorDidChange code.
Changed reuseIdentifier from static to class var to support overrides.
Extracted magic numbers into named constants.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ivanvorobei

Sources/DiffableKit/Table/Cells/DiffableButtonTableViewCell.swift

@@ -1,66 +1,41 @@
 import UIKit
 
-open class DiffableButtonTableViewCell: UITableViewCell {
+open class DiffableButtonTableViewCell: DiffableTableViewCell {
 
-    public static var reuseIdentifier: String { "DiffableButtonTableViewCell" }
+    open override class var reuseIdentifier: String { "DiffableButtonTableViewCell" }
 
-    private var originalImage: UIImage?
+    private static let highlightAlpha: CGFloat = 0.6
+    private static let highlightAnimationDuration: TimeInterval = 0.15
 
     public override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
-        super.init(style: style, reuseIdentifier: reuseIdentifier)
+        super.init(cellStyle: style, reuseIdentifier: reuseIdentifier)
         selectionStyle = .none
     }
 
     public required init?(coder: NSCoder) {
         super.init(coder: coder)
     }
 
-    open override func prepareForReuse() {
-        super.prepareForReuse()
-        originalImage = nil
-        contentConfiguration = nil
-        accessoryView = nil
-    }
-
-    open override func tintColorDidChange() {
-        super.tintColorDidChange()
-        updateDimming()
-    }
-
-    func updateDimming() {
+    override func updateImageDimming() {
         guard var content = contentConfiguration as? UIListContentConfiguration else { return }
         let dimmed = tintAdjustmentMode == .dimmed
-
         let color: UIColor = dimmed ? .secondaryLabel : tintColor
         if content.textProperties.color != color {
             content.textProperties.color = color
+            contentConfiguration = content
         }
-
-        if let image = content.image {
-            if dimmed {
-                if image !== originalImage { originalImage = image }
-                if let desaturated = originalImage?.desaturated() {
-                    content.image = desaturated
-                }
-            } else if let original = originalImage {
-                content.image = original
-                originalImage = nil
-            }
-        }
-
-        contentConfiguration = content
+        super.updateImageDimming()
     }
 
     open override func setHighlighted(_ highlighted: Bool, animated: Bool) {
         super.setHighlighted(highlighted, animated: animated)
-        let alpha: CGFloat = highlighted ? 0.6 : 1
+        let alpha: CGFloat = highlighted ? Self.highlightAlpha : 1
         if animated {
-            UIView.animate(withDuration: 0.15) {
+            UIView.animate(withDuration: Self.highlightAnimationDuration) {
                 self.contentView.subviews.forEach { $0.alpha = alpha }
             }
         } else {
             contentView.subviews.forEach { $0.alpha = alpha }
         }
     }
-
 }

Sources/DiffableKit/Table/Cells/DiffableSubtitleTableViewCell.swift

@@ -1,44 +1,14 @@
 import UIKit
 
-open class DiffableSubtitleTableViewCell: UITableViewCell {
+open class DiffableSubtitleTableViewCell: DiffableTableViewCell {
 
-    public static var reuseIdentifier: String { "DiffableSubtitleTableViewCell" }
-
-    private var originalImage: UIImage?
+    open override class var reuseIdentifier: String { "DiffableSubtitleTableViewCell" }
 
     public override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
-        super.init(style: .subtitle, reuseIdentifier: reuseIdentifier)
+        super.init(cellStyle: .subtitle, reuseIdentifier: reuseIdentifier)
     }
 
     public required init?(coder: NSCoder) {
         super.init(coder: coder)
     }
-
-    open override func prepareForReuse() {
-        super.prepareForReuse()
-        originalImage = nil
-        contentConfiguration = nil
-        accessoryView = nil
-    }
-
-    open override func tintColorDidChange() {
-        super.tintColorDidChange()
-        updateImageDimming()
-    }
-
-    func updateImageDimming() {
-        guard var content = contentConfiguration as? UIListContentConfiguration else { return }
-        let dimmed = tintAdjustmentMode == .dimmed
-        if dimmed {
-            let currentImage = content.image
-            if currentImage !== originalImage { originalImage = currentImage }
-            guard let desaturated = originalImage?.desaturated() else { return }
-            content.image = desaturated
-        } else {
-            guard let original = originalImage else { return }
-            content.image = original
-            originalImage = nil
-        }
-        contentConfiguration = content
-    }
 }

Sources/DiffableKit/Table/Cells/DiffableTableViewCell.swift

@@ -2,14 +2,18 @@ import UIKit
 
 open class DiffableTableViewCell: UITableViewCell {
 
-    public static var reuseIdentifier: String { "DiffableTableViewCell" }
+    open class var reuseIdentifier: String { "DiffableTableViewCell" }
 
     private var originalImage: UIImage?
 
     public override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
         super.init(style: .value1, reuseIdentifier: reuseIdentifier)
     }
 
+    internal init(cellStyle: UITableViewCell.CellStyle, reuseIdentifier: String?) {
+        super.init(style: cellStyle, reuseIdentifier: reuseIdentifier)
+    }
+
     public required init?(coder: NSCoder) {
         super.init(coder: coder)
     }

Sources/DiffableKit/Table/DataSource/DiffableTableDataSource+CellProvider.swift

@@ -87,7 +87,7 @@ extension DiffableTableDataSource {
                 let descriptor = UIFontDescriptor.preferredFontDescriptor(withTextStyle: .body)
                 content.textProperties.font = UIFont.systemFont(ofSize: descriptor.pointSize, weight: .medium)
                 cell.contentConfiguration = content
-                cell.updateDimming()
+                cell.updateImageDimming()
                 cell.accessoryType = item.accessoryType
                 return cell
             }