Support providing additional information to Item callbacks

CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Changed
 
+- Update `Item` callbacks to [allow for providing more info to the callback parameters](https://github.com/kyleve/Listable/pull/160).
+
 ### Misc
 
 # Past Releases

Demo/Sources/Demos/DemosRootViewController.swift

@@ -46,7 +46,8 @@ public final class DemosRootViewController : UIViewController
                     selectionStyle: .tappable,
                     onSelect : { _ in
                         self.push(CollectionViewBasicDemoViewController())
-                })
+                    }
+                )
 
                 section += Item(
                     DemoItem(text: "Blueprint Integration"),

Listable/Sources/Internal/Presentation State/PresentationState.ItemState.swift

@@ -153,6 +153,9 @@ extension PresentationState
 
         private(set) var isDisplayed : Bool = false
 
+        private var hasDisplayed : Bool = false
+        private var hasEndedDisplay : Bool = false
+
         func setAndPerform(isDisplayed: Bool) {
             guard self.isDisplayed != isDisplayed else {
                 return
@@ -161,9 +164,21 @@ extension PresentationState
             self.isDisplayed = isDisplayed
 
             if self.isDisplayed {
-                self.model.onDisplay?(self.model.content)
+                self.model.onDisplay?(.init(
+                    item: self.model,
+                    isFirstDisplay: self.hasDisplayed == false
+                    )
+                )
+
+                self.hasDisplayed = true
             } else {
-                self.model.onEndDisplay?(self.model.content)
+                self.model.onEndDisplay?(.init(
+                    item: self.model,
+                    isFirstEndDisplay: self.hasEndedDisplay == false
+                    )
+                )
+
+                self.hasEndedDisplay = true
             }
         }
 
@@ -288,13 +303,13 @@ extension PresentationState
                 if isSelected {
                     if let onSelect = self.model.onSelect {
                         SignpostLogger.log(log: .listInteraction, name: "Item onSelect", for: self.model) {
-                            onSelect(self.model.content)
+                            onSelect(.init(item: self.model))
                         }
                     }
                 } else {
                     if let onDeselect = self.model.onDeselect {
                         SignpostLogger.log(log: .listInteraction, name: "Item onDeselect", for: self.model) {
-                            onDeselect(self.model.content)
+                            onDeselect(.init(item: self.model))
                         }
                     }
                 }

Listable/Sources/Item/Item.swift

@@ -53,17 +53,10 @@ public struct Item<Content:ItemContent> : AnyItem
 
     public var reordering : Reordering?
 
-    public typealias OnSelect = (Content) -> ()
-    public var onSelect : OnSelect?
-
-    public typealias OnDeselect = (Content) -> ()
-    public var onDeselect : OnDeselect?
-
-    public typealias OnDisplay = (Content) -> ()
-    public var onDisplay : OnDisplay?
-
-    public typealias OnEndDisplay = (Content) -> ()
-    public var onEndDisplay : OnEndDisplay?
+    public var onSelect : OnSelect.Callback?
+    public var onDeselect : OnDeselect.Callback?
+    public var onDisplay : OnDisplay.Callback?
+    public var onEndDisplay : OnEndDisplay.Callback?
 
     internal let reuseIdentifier : ReuseIdentifier<Content>
 
@@ -92,10 +85,10 @@ public struct Item<Content:ItemContent> : AnyItem
         selectionStyle : ItemSelectionStyle? = nil,
         swipeActions : SwipeActionsConfiguration? = nil,
         reordering : Reordering? = nil,
-        onDisplay : OnDisplay? = nil,
-        onEndDisplay : OnEndDisplay? = nil,
-        onSelect : OnSelect? = nil,
-        onDeselect : OnDeselect? = nil
+        onDisplay : OnDisplay.Callback? = nil,
+        onEndDisplay : OnEndDisplay.Callback? = nil,
+        onSelect : OnSelect.Callback? = nil,
+        onDeselect : OnDeselect.Callback? = nil
         )
     {
         self.content = content
@@ -172,6 +165,46 @@ public struct Item<Content:ItemContent> : AnyItem
 }
 
 
+public extension Item
+{
+    /// Value passed to the `onSelect` callback for `Item`.
+    struct OnSelect
+    {
+        public typealias Callback = (OnSelect) -> ()
+
+        public var item : Item
+    }
+
+    /// Value passed to the `onDeselect` callback for `Item`.
+    struct OnDeselect
+    {
+        public typealias Callback = (OnDeselect) -> ()
+
+        public var item : Item
+    }
+
+    /// Value passed to the `onDisplay` callback for `Item`.
+    struct OnDisplay
+    {
+        public typealias Callback = (OnDisplay) -> ()
+
+        public var item : Item
+
+        public var isFirstDisplay : Bool
+    }
+
+    /// Value passed to the `onEndDisplay` callback for `Item`.
+    struct OnEndDisplay
+    {
+        public typealias Callback = (OnEndDisplay) -> ()
+
+        public var item : Item
+
+        public var isFirstEndDisplay : Bool
+    }
+}
+
+
 /// Allows specifying default properties to apply to an item when it is initialized,
 /// if those values are not provided to the initializer.
 /// Only non-nil values are used – if you do not want to provide a default value,