Add layout logic and models

Example iOS/Controllers/PresetsController.swift

@@ -2,9 +2,10 @@ import UIKit
 import SparrowKit
 import SPDiffable
 
-// Maybe ding toolbar
 class PresetsController: SPDiffableTableController {
     
+    // MARK: - Init
+    
     init() {
         super.init(style: .insetGrouped)
     }
@@ -13,15 +14,27 @@ class PresetsController: SPDiffableTableController {
         fatalError("init(coder:) has not been implemented")
     }
     
+    // MARK: - Lifecycle
+    
     override func viewDidLoad() {
         super.viewDidLoad()
         navigationItem.title = "SPAlert Presets"
+        
+        currentPreset = presets.first!
         setCellProviders(SPDiffableTableCellProviders.default, sections: content)
         
         navigationController?.isToolbarHidden = false
         toolbarItems = [
-            .init(image: .system("chevron.down.circle.fill"), primaryAction: .init(handler: { (action) in
-                #warning("doing next switch")
+            .init(image: .system("chevron.down.circle"), primaryAction: .init(handler: { (action) in
+                guard let currentPreset = self.currentPreset else {
+                    self.currentPreset = self.presets.first
+                    return
+                }
+                guard let index = self.presets.firstIndex(where: { $0.id == currentPreset.id }) else { return }
+                self.currentPreset = self.presets[safe: index + 1]
+                if self.currentPreset == nil {
+                    self.currentPreset = self.presets.first
+                }
             })),
             .init(barButtonSystemItem: .flexibleSpace, target: nil, action: nil),
             .init(systemItem: .play, primaryAction: .init(handler: { (action) in
@@ -31,6 +44,8 @@ class PresetsController: SPDiffableTableController {
         ]
     }
     
+    // MARK: - Data
+    
     fileprivate var presets: [AlertPreset] {
         return [
             AlertPreset(name: "Done", preset: .done),
@@ -38,10 +53,29 @@ class PresetsController: SPDiffableTableController {
         ]
     }
     
+    // MARK: - Diffable
+    
+    var currentPreset: AlertPreset? {
+        willSet {
+            guard let id = self.currentPreset?.id else { return }
+            let cell = diffableDataSource?.cell(UITableViewCell.self, for: id)
+            cell?.accessoryType = .none
+        }
+        didSet {
+            guard let id = self.currentPreset?.id else { return }
+            let cell = diffableDataSource?.cell(UITableViewCell.self, for: id)
+            cell?.accessoryType = .checkmark
+        }
+    }
+    
     var content: [SPDiffableSection] {
         let items = presets.map { (preset) -> SPDiffableTableRow in
-            return SPDiffableTableRow(text: preset.name, accessoryType: .none, selectionStyle: .none) { (_) in
-                return
+            return SPDiffableTableRow(
+                text: preset.name,
+                accessoryType: (preset.id == currentPreset?.id) ? .checkmark : .none,
+                selectionStyle: .none) { [weak self] _ in
+                    guard let self = self else { return }
+                    self.currentPreset = preset
             }
         }
         return [
@@ -49,9 +83,3 @@ class PresetsController: SPDiffableTableController {
         ]
     }
 }
-
-struct AlertPreset {
-    
-    var name: String
-    var preset: SPAlertPreset
-}